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class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Origins"> <div class="vector-toc-text"> 2.1 Origins </div> </a> <ul id="toc-Origins-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Definition_process" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Definition_process"> <div class="vector-toc-text"> 2.2 Definition process </div> </a> <ul id="toc-Definition_process-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Publication" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Publication"> <div class="vector-toc-text"> 2.3 Publication </div> </a> <ul id="toc-Publication-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Implementations" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Implementations"> <div class="vector-toc-text"> 2.4 Implementations </div> </a> <ul id="toc-Implementations-sublist" class="vector-toc-list"> <li id="toc-ALGOL_68-R" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#ALGOL_68-R"> <div class="vector-toc-text"> 2.4.1 ALGOL 68-R </div> </a> <ul id="toc-ALGOL_68-R-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Others" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Others"> <div class="vector-toc-text"> 2.4.2 Others </div> </a> <ul id="toc-Others-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Timeline" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Timeline"> <div class="vector-toc-text"> 2.5 Timeline </div> </a> <ul id="toc-Timeline-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-The_Algorithmic_Language_ALGOL_68_Reports_and_Working_Group_members" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#The_Algorithmic_Language_ALGOL_68_Reports_and_Working_Group_members"> <div class="vector-toc-text"> 2.6 The Algorithmic Language ALGOL 68 Reports and Working Group members </div> </a> <ul id="toc-The_Algorithmic_Language_ALGOL_68_Reports_and_Working_Group_members-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Timeline_of_standardization" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Timeline_of_standardization"> <div class="vector-toc-text"> 2.7 Timeline of standardization </div> </a> <ul id="toc-Timeline_of_standardization-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Notable_language_elements" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Notable_language_elements"> <div class="vector-toc-text"> 3 Notable language elements </div> </a> <button aria-controls="toc-Notable_language_elements-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Notable language elements subsection </button> <ul id="toc-Notable_language_elements-sublist" class="vector-toc-list"> <li id="toc-Bold_symbols_and_reserved_words" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Bold_symbols_and_reserved_words"> <div class="vector-toc-text"> 3.1 Bold symbols and reserved words </div> </a> <ul id="toc-Bold_symbols_and_reserved_words-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Units:_Expressions" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Units:_Expressions"> <div class="vector-toc-text"> 3.2 Units: Expressions </div> </a> <ul id="toc-Units:_Expressions-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-mode:_Declarations" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#mode:_Declarations"> <div class="vector-toc-text"> 3.3 mode: Declarations </div> </a> <ul id="toc-mode:_Declarations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Coercions:_casting" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Coercions:_casting"> <div class="vector-toc-text"> 3.4 Coercions: casting </div> </a> <ul id="toc-Coercions:_casting-sublist" class="vector-toc-list"> <li id="toc-Coercion_hierarchy_with_examples" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Coercion_hierarchy_with_examples"> <div class="vector-toc-text"> 3.4.1 Coercion hierarchy with examples </div> </a> <ul id="toc-Coercion_hierarchy_with_examples-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-pr_&_co:_Pragmats_and_Comments" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#pr_&_co:_Pragmats_and_Comments"> <div class="vector-toc-text"> 3.5 pr & co: Pragmats and Comments </div> </a> <ul id="toc-pr_&_co:_Pragmats_and_Comments-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Expressions_and_compound_statements" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Expressions_and_compound_statements"> <div class="vector-toc-text"> 3.6 Expressions and compound statements </div> </a> <ul id="toc-Expressions_and_compound_statements-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-struct,_union_&_[:]:_Structures,_unions_and_arrays" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#struct,_union_&_[:]:_Structures,_unions_and_arrays"> <div class="vector-toc-text"> 3.7 struct, union & [:]: Structures, unions and arrays </div> </a> <ul id="toc-struct,_union_&_[:]:_Structures,_unions_and_arrays-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-proc:_Procedures" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#proc:_Procedures"> <div class="vector-toc-text"> 3.8 proc: Procedures </div> </a> <ul id="toc-proc:_Procedures-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-op:_Operators" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#op:_Operators"> <div class="vector-toc-text"> 3.9 op: Operators </div> </a> <ul id="toc-op:_Operators-sublist" class="vector-toc-list"> <li id="toc-Array,_Procedure,_Dereference_and_coercion_operations" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Array,_Procedure,_Dereference_and_coercion_operations"> <div class="vector-toc-text"> 3.9.1 Array, Procedure, Dereference and coercion operations </div> </a> <ul id="toc-Array,_Procedure,_Dereference_and_coercion_operations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Monadic_operators" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Monadic_operators"> <div class="vector-toc-text"> 3.9.2 Monadic operators </div> </a> <ul id="toc-Monadic_operators-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Dyadic_operators_with_associated_priorities" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Dyadic_operators_with_associated_priorities"> <div class="vector-toc-text"> 3.9.3 Dyadic operators with associated priorities </div> </a> <ul id="toc-Dyadic_operators_with_associated_priorities-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Assignation_and_identity_relations,_etc." class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Assignation_and_identity_relations,_etc."> <div class="vector-toc-text"> 3.9.4 Assignation and identity relations, etc. </div> </a> <ul id="toc-Assignation_and_identity_relations,_etc.-sublist" class="vector-toc-list"> <li id="toc-Why_:=:_and_:/=:_are_needed" class="vector-toc-list-item vector-toc-level-4"> <a class="vector-toc-link" href="#Why_:=:_and_:/=:_are_needed"> <div class="vector-toc-text"> 3.9.4.1 Why :=: and :/=: are needed </div> </a> <ul id="toc-Why_:=:_and_:/=:_are_needed-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Special_characters" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Special_characters"> <div class="vector-toc-text"> 3.9.5 Special characters </div> </a> <ul id="toc-Special_characters-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-transput:_Input_and_output" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#transput:_Input_and_output"> <div class="vector-toc-text"> 3.10 transput: Input and output </div> </a> <ul id="toc-transput:_Input_and_output-sublist" class="vector-toc-list"> <li id="toc-Books,_channels_and_files" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#Books,_channels_and_files"> <div class="vector-toc-text"> 3.10.1 Books, channels and files </div> </a> <ul id="toc-Books,_channels_and_files-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-formatted_transput" class="vector-toc-list-item vector-toc-level-3"> <a class="vector-toc-link" href="#formatted_transput"> <div class="vector-toc-text"> 3.10.2 formatted transput </div> </a> <ul id="toc-formatted_transput-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-par:_Parallel_processing" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#par:_Parallel_processing"> <div class="vector-toc-text"> 3.11 par: Parallel processing </div> </a> <ul id="toc-par:_Parallel_processing-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Miscellaneous" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Miscellaneous"> <div class="vector-toc-text"> 3.12 Miscellaneous </div> </a> <ul id="toc-Miscellaneous-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Examples_of_use" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Examples_of_use"> <div class="vector-toc-text"> 4 Examples of use </div> </a> <button aria-controls="toc-Examples_of_use-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Examples of use subsection </button> <ul id="toc-Examples_of_use-sublist" class="vector-toc-list"> <li id="toc-Code_sample" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Code_sample"> <div class="vector-toc-text"> 4.1 Code sample </div> </a> <ul id="toc-Code_sample-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Operating_systems_written_in_ALGOL_68" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Operating_systems_written_in_ALGOL_68"> <div class="vector-toc-text"> 4.2 Operating systems written in ALGOL 68 </div> </a> <ul id="toc-Operating_systems_written_in_ALGOL_68-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Applications" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Applications"> <div class="vector-toc-text"> 4.3 Applications </div> </a> <ul id="toc-Applications-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Libraries_and_APIs" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Libraries_and_APIs"> <div class="vector-toc-text"> 4.4 Libraries and APIs </div> </a> <ul id="toc-Libraries_and_APIs-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Program_representation" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Program_representation"> <div class="vector-toc-text"> 5 Program representation </div> </a> <button aria-controls="toc-Program_representation-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Program representation subsection </button> <ul id="toc-Program_representation-sublist" class="vector-toc-list"> <li id="toc-Example_of_different_program_representations" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Example_of_different_program_representations"> <div class="vector-toc-text"> 5.1 Example of different program representations </div> </a> <ul id="toc-Example_of_different_program_representations-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Revisions" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Revisions"> <div class="vector-toc-text"> 6 Revisions </div> </a> <button aria-controls="toc-Revisions-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Revisions subsection </button> <ul id="toc-Revisions-sublist" class="vector-toc-list"> <li id="toc-The_language_of_the_unrevised_report" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#The_language_of_the_unrevised_report"> <div class="vector-toc-text"> 6.1 The language of the unrevised report </div> </a> <ul id="toc-The_language_of_the_unrevised_report-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Extension_proposals_from_IFIP_WG_2.1" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Extension_proposals_from_IFIP_WG_2.1"> <div class="vector-toc-text"> 6.2 Extension proposals from IFIP WG 2.1 </div> </a> <ul id="toc-Extension_proposals_from_IFIP_WG_2.1-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-True_ALGOL_68s_specification_and_implementation_timeline" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#True_ALGOL_68s_specification_and_implementation_timeline"> <div class="vector-toc-text"> 6.3 True ALGOL 68s specification and implementation timeline </div> </a> <ul id="toc-True_ALGOL_68s_specification_and_implementation_timeline-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Implementation_specific_extensions" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Implementation_specific_extensions"> <div class="vector-toc-text"> 6.4 Implementation specific extensions </div> </a> <ul id="toc-Implementation_specific_extensions-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Quotes" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Quotes"> <div class="vector-toc-text"> 7 Quotes </div> </a> <ul id="toc-Quotes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-See_also" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#See_also"> <div class="vector-toc-text"> 8 See also </div> </a> <ul id="toc-See_also-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> 9 References </div> </a> <button aria-controls="toc-References-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle References subsection </button> <ul id="toc-References-sublist" class="vector-toc-list"> <li id="toc-Citations" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Citations"> <div class="vector-toc-text"> 9.1 Citations </div> </a> <ul id="toc-Citations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Works_cited" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Works_cited"> <div class="vector-toc-text"> 9.2 Works cited </div> </a> <ul id="toc-Works_cited-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> 10 External links </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Toggle the table of contents" > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" > Toggle the table of contents </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading">ALGOL 68</h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 17 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-17" aria-hidden="true" > 17 languages </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%A7%D9%84%D8%BA%D9%88%D9%84_68" title="الغول 68 – Arabic" lang="ar" hreflang="ar" data-title="الغول 68" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target">العربية</a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Algol_68" title="Algol 68 – German" lang="de" hreflang="de" data-title="Algol 68" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target">Deutsch</a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%A7%D9%84%DA%AF%D9%88%D9%84%DB%B6%DB%B8" title="الگول۶۸ – Persian" lang="fa" hreflang="fa" data-title="الگول۶۸" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target">فارسی</a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Algol_68" title="Algol 68 – French" lang="fr" hreflang="fr" data-title="Algol 68" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target">Français</a></li><li class="interlanguage-link interwiki-io mw-list-item"><a href="https://io.wikipedia.org/wiki/ALGOL_68" title="ALGOL 68 – Ido" lang="io" hreflang="io" data-title="ALGOL 68" data-language-autonym="Ido" data-language-local-name="Ido" class="interlanguage-link-target">Ido</a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%86%E0%B5%BD%E0%B4%97%E0%B5%8B%E0%B5%BE_68" title="ആൽഗോൾ 68 – Malayalam" lang="ml" hreflang="ml" data-title="ആൽഗോൾ 68" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target">മലയാളം</a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/Algol_68" title="Algol 68 – Dutch" lang="nl" hreflang="nl" data-title="Algol 68" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target">Nederlands</a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/ALGOL_68" title="ALGOL 68 – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="ALGOL 68" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target">Norsk bokmål</a></li><li class="interlanguage-link interwiki-pa mw-list-item"><a href="https://pa.wikipedia.org/wiki/%E0%A8%90%E0%A8%B2%E0%A8%97%E0%A9%8C%E0%A8%B2_68" title="ਐਲਗੌਲ 68 – Punjabi" lang="pa" hreflang="pa" data-title="ਐਲਗੌਲ 68" data-language-autonym="ਪੰਜਾਬੀ" data-language-local-name="Punjabi" class="interlanguage-link-target">ਪੰਜਾਬੀ</a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/ALGOL_68" title="ALGOL 68 – Portuguese" lang="pt" hreflang="pt" data-title="ALGOL 68" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target">Português</a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%90%D0%BB%D0%B3%D0%BE%D0%BB_68" title="Алгол 68 – Russian" lang="ru" hreflang="ru" data-title="Алгол 68" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target">Русский</a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/ALGOL_68" title="ALGOL 68 – Slovak" lang="sk" hreflang="sk" data-title="ALGOL 68" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target">Slovenčina</a></li><li class="interlanguage-link interwiki-tg mw-list-item"><a href="https://tg.wikipedia.org/wiki/%D0%90%D0%BB%D0%B3%D0%BE%D0%BB_68" title="Алгол 68 – Tajik" lang="tg" hreflang="tg" data-title="Алгол 68" data-language-autonym="Тоҷикӣ" data-language-local-name="Tajik" class="interlanguage-link-target">Тоҷикӣ</a></li><li class="interlanguage-link interwiki-tr mw-list-item"><a href="https://tr.wikipedia.org/wiki/ALGOL_68" title="ALGOL 68 – Turkish" lang="tr" hreflang="tr" data-title="ALGOL 68" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target">Türkçe</a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/ALGOL_68" title="ALGOL 68 – Vietnamese" lang="vi" hreflang="vi" data-title="ALGOL 68" data-language-autonym="Tiếng Việt" data-language-local-name="Vietnamese" class="interlanguage-link-target">Tiếng Việt</a></li><li class="interlanguage-link interwiki-zh-yue mw-list-item"><a href="https://zh-yue.wikipedia.org/wiki/ALGOL_68" title="ALGOL 68 – Cantonese" lang="yue" hreflang="yue" data-title="ALGOL 68" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target">粵語</a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/ALGOL_68" title="ALGOL 68 – Chinese" lang="zh" hreflang="zh" data-title="ALGOL 68" data-language-autonym="中文" data-language-local-name="Chinese" class="interlanguage-link-target">中文</a></li> </ul> <div class="after-portlet after-portlet-lang"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q2166735#sitelinks-wikipedia" title="Edit interlanguage links" class="wbc-editpage">Edit links</a></div> </div> </div> </div> </header> <div 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<div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Programming language</div> <style data-mw-deduplicate="TemplateStyles:r1257001546">.mw-parser-output .infobox-subbox{padding:0;border:none;margin:-3px;width:auto;min-width:100%;font-size:100%;clear:none;float:none;background-color:transparent}.mw-parser-output .infobox-3cols-child{margin:auto}.mw-parser-output .infobox .navbar{font-size:100%}@media screen{html.skin-theme-clientpref-night .mw-parser-output .infobox-full-data:not(.notheme)>div:not(.notheme)[style]{background:#1f1f23!important;color:#f8f9fa}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox-full-data:not(.notheme) div:not(.notheme){background:#1f1f23!important;color:#f8f9fa}}@media(min-width:640px){body.skin--responsive .mw-parser-output .infobox-table{display:table!important}body.skin--responsive .mw-parser-output .infobox-table>caption{display:table-caption!important}body.skin--responsive .mw-parser-output .infobox-table>tbody{display:table-row-group}body.skin--responsive .mw-parser-output .infobox-table tr{display:table-row!important}body.skin--responsive .mw-parser-output .infobox-table th,body.skin--responsive .mw-parser-output .infobox-table td{padding-left:inherit;padding-right:inherit}}</style><table class="infobox vevent"><caption class="infobox-title summary">ALGOL 68</caption><tbody><tr><td colspan="2" class="infobox-image"><a href="/wiki/File:Algol68RevisedReportCover.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/en/thumb/3/35/Algol68RevisedReportCover.jpg/121px-Algol68RevisedReportCover.jpg" decoding="async" width="121" height="179" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/3/35/Algol68RevisedReportCover.jpg/182px-Algol68RevisedReportCover.jpg 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/3/35/Algol68RevisedReportCover.jpg/242px-Algol68RevisedReportCover.jpg 2x" data-file-width="259" data-file-height="383" /></a><div class="infobox-caption">Revised Report on the Algorithmic Language – Algol 68 Edited by: A. van Wijngaarden et al, September 1973<a href="#cite_note-Wijngaarden_1976-1">[1]</a></div></td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Programming_paradigm" title="Programming paradigm">Paradigms</a></th><td class="infobox-data"><a href="/wiki/Multi-paradigm_programming_language" class="mw-redirect" title="Multi-paradigm programming language">Multi-paradigm</a>: <a href="/wiki/Concurrent_programming_language" class="mw-redirect" title="Concurrent programming language">concurrent</a>, <a href="/wiki/Imperative_programming" title="Imperative programming">imperative</a></td></tr><tr><th scope="row" class="infobox-label">Family</th><td class="infobox-data"><a href="/wiki/ALGOL" title="ALGOL">ALGOL</a></td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Software_design" title="Software design">Designed by</a></th><td class="infobox-data"><a href="/wiki/Adriaan_van_Wijngaarden" title="Adriaan van Wijngaarden">A. van Wijngaarden</a>, <a href="/wiki/Barry_J._Mailloux" title="Barry J. Mailloux">B. J. Mailloux</a>, <a href="/wiki/John_E._L._Peck" title="John E. L. Peck">J. E. L. Peck</a> and <a href="/wiki/Cornelis_H._A._Koster" title="Cornelis H. A. Koster">C. H. A. Koster</a>, et al.</td></tr><tr><th scope="row" class="infobox-label">First appeared</th><td class="infobox-data">Final Report: 1968; 56 years ago (1968)<a href="#The_language_of_the_unrevised_report">r0</a></td></tr><tr><td colspan="2" class="infobox-full-data"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1257001546"></td></tr><tr><th scope="row" class="infobox-label" style="white-space: nowrap;"><a href="/wiki/Software_release_life_cycle" title="Software release life cycle">Stable release</a></th><td class="infobox-data"><div style="margin:0px;">Algol 68/RR / Revised Report: 1973; 51 years ago (1973)<a href="#Revisions">r1</a></div></td></tr><tr style="display:none"><td colspan="2"> </td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Type_system" title="Type system">Typing discipline</a></th><td class="infobox-data"><a href="/wiki/Type_system#Type_checking" title="Type system">static</a>, <a href="/wiki/Strong_and_weak_typing" title="Strong and weak typing">strong</a>, <a href="/wiki/Type_system#Safely_and_unsafely_typed_systems" title="Type system">safe</a>, <a href="/wiki/Structural_type_system" title="Structural type system">structural</a></td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Scope_(computer_science)" title="Scope (computer science)">Scope</a></th><td class="infobox-data"><a href="/wiki/Scope_(computer_science)" title="Scope (computer science)">Lexical</a></td></tr><tr><th colspan="2" class="infobox-header" style="background-color: #eee;">Major <a href="/wiki/Programming_language_implementation" title="Programming language implementation">implementations</a></th></tr><tr><td colspan="2" class="infobox-full-data"><a href="/wiki/ALGOL_68C" title="ALGOL 68C">ALGOL 68C</a>, Algol 68 Genie (recent), <a href="/wiki/ALGOL_68-R" title="ALGOL 68-R">ALGOL 68-R</a>, <a href="/wiki/ALGOL_68RS" title="ALGOL 68RS">ALGOL 68RS</a>, <a href="/wiki/ALGOL_68S" title="ALGOL 68S">ALGOL 68S</a>, <a href="/wiki/FLACC" title="FLACC">FLACC</a>, <a href="https://ru.wikipedia.org/wiki/%D0%90%D0%BB%D0%B3%D0%BE%D0%BB_68" class="extiw" title="ru:Алгол 68">Алгол 68 Ленинград/Leningrad Unit</a>, <a href="/wiki/Odra_(computer)" title="Odra (computer)">Odra ALGOL 68</a></td></tr><tr><th colspan="2" class="infobox-header" style="background-color: #eee;"><a href="/wiki/Programming_language#Dialects,_flavors_and_implementations" title="Programming language">Dialects</a></th></tr><tr><td colspan="2" class="infobox-full-data">ALGOL 68/FR (Final Report<a href="#The_language_of_the_unrevised_report">r0</a>)</td></tr><tr><th colspan="2" class="infobox-header" style="background-color: #eee;">Influenced by</th></tr><tr><td colspan="2" class="infobox-full-data"><a href="/wiki/ALGOL_60" title="ALGOL 60">ALGOL 60</a>, <a href="/wiki/ALGOL_Y" title="ALGOL Y">ALGOL Y</a></td></tr><tr><th colspan="2" class="infobox-header" style="background-color: #eee;">Influenced</th></tr><tr><td colspan="2" class="infobox-full-data"><a href="/wiki/C_(programming_language)" title="C (programming language)">C</a>,<a href="#cite_note-3">[3]</a><a href="#cite_note-5">[5]</a> <a href="/wiki/C%2B%2B" title="C++">C++</a>,<a href="#cite_note-a68-c++-6">[6]</a> <a href="/wiki/Bourne_shell" title="Bourne shell">Bourne shell</a>, <a href="/wiki/KornShell" title="KornShell">KornShell</a>, <a href="/wiki/Bash_(Unix_shell)" title="Bash (Unix shell)">Bash</a>, <a href="/wiki/Steelman_language_requirements" title="Steelman language requirements">Steelman</a>, <a href="/wiki/Ada_(programming_language)" title="Ada (programming language)">Ada</a>, <a href="/wiki/Python_(programming_language)" title="Python (programming language)">Python</a>,<a href="#cite_note-a68-python-7">[7]</a> <a href="/wiki/Seed7" title="Seed7">Seed7</a>, <a href="/wiki/Mary_(programming_language)" title="Mary (programming language)">Mary</a>, <a href="/wiki/S3_(programming_language)" title="S3 (programming language)">S3</a></td></tr></tbody></table> <style data-mw-deduplicate="TemplateStyles:r1235681985">.mw-parser-output .side-box{margin:4px 0;box-sizing:border-box;border:1px solid #aaa;font-size:88%;line-height:1.25em;background-color:var(--background-color-interactive-subtle,#f8f9fa);display:flow-root}.mw-parser-output .side-box-abovebelow,.mw-parser-output .side-box-text{padding:0.25em 0.9em}.mw-parser-output .side-box-image{padding:2px 0 2px 0.9em;text-align:center}.mw-parser-output .side-box-imageright{padding:2px 0.9em 2px 0;text-align:center}@media(min-width:500px){.mw-parser-output .side-box-flex{display:flex;align-items:center}.mw-parser-output .side-box-text{flex:1;min-width:0}}@media(min-width:720px){.mw-parser-output .side-box{width:238px}.mw-parser-output .side-box-right{clear:right;float:right;margin-left:1em}.mw-parser-output .side-box-left{margin-right:1em}}</style><style data-mw-deduplicate="TemplateStyles:r1092331828">@media(min-width:720px){.mw-parser-output .contains-special-characters{width:22em}}</style><div class="side-box metadata side-box-right contains-special-characters noprint selfref"><style data-mw-deduplicate="TemplateStyles:r1126788409">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style> <div class="side-box-flex"> <div class="side-box-text plainlist">This article contains Unicode 6.0 "<a rel="nofollow" class="external text" href="https://www.unicode.org/charts/PDF/U2300.pdf">Miscellaneous Technical</a>" characters. Without proper <a href="/wiki/Unicode#External_links" title="Unicode">rendering support</a>, you may see <a href="/wiki/Specials_(Unicode_block)#Replacement_character" title="Specials (Unicode block)">question marks, boxes, or other symbols</a> instead of something like "₁₀" (<a rel="nofollow" class="external text" href="http://mailcom.com/unicode/DecimalExponent.ttf">Decimal Exponent Symbol U+23E8 TTF</a>).</div></div> </div> ALGOL 68 (short for Algorithmic Language 1968) is an <a href="/wiki/Imperative_programming" title="Imperative programming">imperative</a> <a href="/wiki/Programming_language" title="Programming language">programming language</a> that was conceived as a successor to the <a href="/wiki/ALGOL_60" title="ALGOL 60">ALGOL 60</a> programming language, designed with the goal of a much wider scope of application and more rigorously defined <a href="/wiki/Syntax_(programming_languages)" title="Syntax (programming languages)">syntax</a> and semantics. The complexity of the language's definition, which runs to several hundred pages filled with non-standard terminology, made <a href="/wiki/Compiler" title="Compiler">compiler</a> implementation difficult and it was said it had "no implementations and no users". This was only partly true; ALGOL 68 did find use in several niche markets, notably in the <a href="/wiki/United_Kingdom" title="United Kingdom">United Kingdom</a> where it was popular on <a href="/wiki/International_Computers_Limited" title="International Computers Limited">International Computers Limited</a> (ICL) machines, and in teaching roles. Outside these fields, use was relatively limited. Nevertheless, the contributions of ALGOL 68 to the field of <a href="/wiki/Computer_science" title="Computer science">computer science</a> have been deep, wide-ranging and enduring, although many of these contributions were only publicly identified when they had reappeared in subsequently developed programming languages. Many languages were developed specifically as a response to the perceived complexity of the language, the most notable being <a href="/wiki/Pascal_(programming_language)" title="Pascal (programming language)">Pascal</a>, or were reimplementations for specific roles, like <a href="/wiki/Ada_(programming_language)" title="Ada (programming language)">Ada</a>. Many languages of the 1970s trace their design specifically to ALGOL 68, selecting some features while abandoning others that were considered too complex or out-of-scope for given roles. Among these is the language <a href="/wiki/C_(programming_language)" title="C (programming language)">C</a>, which was directly influenced by ALGOL 68, especially by its <a href="/wiki/Strong_and_weak_typing" title="Strong and weak typing">strong typing</a> and structures. Most modern languages trace at least some of their syntax to either C or Pascal, and thus directly or indirectly to ALGOL 68. <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Overview">Overview</h2>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=1" title="Edit section: Overview">edit</a>]</div> ALGOL 68 features include expression-based syntax, user-declared types and structures/tagged-unions, a reference model of variables and reference parameters, string, array and matrix slicing, and concurrency. ALGOL 68 was designed by the <a href="/wiki/International_Federation_for_Information_Processing" title="International Federation for Information Processing">International Federation for Information Processing</a> (IFIP) <a href="/wiki/IFIP_Working_Group_2.1" title="IFIP Working Group 2.1">IFIP Working Group 2.1</a> on Algorithmic Languages and Calculi. On December 20, 1968, the language was formally adopted by the group, and then approved for publication by the General Assembly of IFIP. ALGOL 68 was defined using a <a href="/wiki/Formalism_(philosophy_of_mathematics)" title="Formalism (philosophy of mathematics)">formalism</a>, a two-level <a href="/wiki/Formal_grammar" title="Formal grammar">formal grammar</a>, invented by <a href="/wiki/Adriaan_van_Wijngaarden" title="Adriaan van Wijngaarden">Adriaan van Wijngaarden</a>. <a href="/wiki/Van_Wijngaarden_grammar" title="Van Wijngaarden grammar">Van Wijngaarden grammars</a> use a <a href="/wiki/Context-free_grammar" title="Context-free grammar">context-free grammar</a> to generate an infinite set of productions that will recognize a particular ALGOL 68 program; notably, they are able to express the kind of requirements that in many other programming language <a href="/wiki/Technical_standard" title="Technical standard">technical standards</a> are labelled semantics, and must be expressed in ambiguity-prone natural language prose, and then implemented in compilers as ad hoc code attached to the formal language parser. <style data-mw-deduplicate="TemplateStyles:r1224211176">.mw-parser-output .quotebox{background-color:#F9F9F9;border:1px solid #aaa;box-sizing:border-box;padding:10px;font-size:88%;max-width:100%}.mw-parser-output .quotebox.floatleft{margin:.5em 1.4em .8em 0}.mw-parser-output .quotebox.floatright{margin:.5em 0 .8em 1.4em}.mw-parser-output .quotebox.centered{overflow:hidden;position:relative;margin:.5em auto .8em auto}.mw-parser-output .quotebox.floatleft span,.mw-parser-output .quotebox.floatright span{font-style:inherit}.mw-parser-output .quotebox>blockquote{margin:0;padding:0;border-left:0;font-family:inherit;font-size:inherit}.mw-parser-output .quotebox-title{text-align:center;font-size:110%;font-weight:bold}.mw-parser-output .quotebox-quote>:first-child{margin-top:0}.mw-parser-output .quotebox-quote:last-child>:last-child{margin-bottom:0}.mw-parser-output .quotebox-quote.quoted:before{font-family:"Times New Roman",serif;font-weight:bold;font-size:large;color:gray;content:" “ ";vertical-align:-45%;line-height:0}.mw-parser-output .quotebox-quote.quoted:after{font-family:"Times New Roman",serif;font-weight:bold;font-size:large;color:gray;content:" ” ";line-height:0}.mw-parser-output .quotebox .left-aligned{text-align:left}.mw-parser-output .quotebox .right-aligned{text-align:right}.mw-parser-output .quotebox .center-aligned{text-align:center}.mw-parser-output .quotebox .quote-title,.mw-parser-output .quotebox .quotebox-quote{display:block}.mw-parser-output .quotebox cite{display:block;font-style:normal}@media screen and (max-width:640px){.mw-parser-output .quotebox{width:100%!important;margin:0 0 .8em!important;float:none!important}}</style><div class="quotebox pullquote floatright" style="; width: 23em;"> <blockquote class="quotebox-quote left-aligned" style=""> ALGOL 68 was the first (and possibly one of the last) major language for which a full formal definition was made before it was implemented. </blockquote> <cite class="left-aligned" style=""><a href="/wiki/Cornelis_H._A._Koster" title="Cornelis H. A. Koster">C. H. A. Koster</a><a href="#cite_note-ashoa68-8">[8]</a></cite> </div> The main aims and principles of design of ALGOL 68: <ol><li>Completeness and clarity of description<a href="#cite_note-completeness-9">[9]</a></li> <li><a href="/wiki/Orthogonality" title="Orthogonality">Orthogonality</a> of design<a href="#cite_note-orthogonality-10">[10]</a></li> <li>Security<a href="#cite_note-security-11">[11]</a></li> <li>Efficiency:<a href="#cite_note-efficiency-12">[12]</a> <ul><li>Static mode checking</li> <li>Mode-independent parsing</li> <li>Independent compiling</li> <li>Loop optimizing</li> <li>Representations – in minimal & larger <a href="/wiki/Character_encoding" title="Character encoding">character sets</a></li></ul></li></ol> ALGOL 68 has been criticized, most prominently by some members of its design committee such as <a href="/wiki/C._A._R._Hoare" class="mw-redirect" title="C. A. R. Hoare">C. A. R. Hoare</a> and <a href="/wiki/Edsger_Dijkstra" class="mw-redirect" title="Edsger Dijkstra">Edsger Dijkstra</a>, for abandoning the simplicity of <a href="/wiki/ALGOL_60" title="ALGOL 60">ALGOL 60</a>, becoming a vehicle for complex or overly general ideas, and doing little to make the <a href="/wiki/Compiler" title="Compiler">compiler</a> writer's task easier, in contrast to deliberately simple contemporaries (and competitors) such as <a href="/wiki/C_(programming_language)" title="C (programming language)">C</a>, <a href="/wiki/S-algol" title="S-algol">S-algol</a> and <a href="/wiki/Pascal_(programming_language)" title="Pascal (programming language)">Pascal</a>. In 1970, <a href="/wiki/ALGOL_68-R" title="ALGOL 68-R">ALGOL 68-R</a> became the first working compiler for ALGOL 68. In the 1973 revision, certain features — such as <a href="/wiki/ALGOL_68-R#No_proceduring" title="ALGOL 68-R">proceduring</a>, gommas<a href="#cite_note-13">[13]</a> and <a href="/wiki/ALGOL_68-R#No_formal_declarers" title="ALGOL 68-R">formal bounds</a> — were omitted.<a href="#cite_note-a68r0-jmvdveer-14">[14]</a> C.f. <a href="#The_language_of_the_unrevised_report">The language of the unrevised report.r0</a> Though European defence agencies (in Britain <a href="/wiki/Royal_Signals_and_Radar_Establishment" title="Royal Signals and Radar Establishment">Royal Signals and Radar Establishment</a> (RSRE)) promoted the use of ALGOL 68 for its expected security advantages, the American side of the NATO alliance decided to develop a different project, the language <a href="/wiki/Ada_(programming_language)" title="Ada (programming language)">Ada</a>, making its use obligatory for US defense contracts. ALGOL 68 also had a notable influence in the <a href="/wiki/Soviet_Union" title="Soviet Union">Soviet Union</a>, details of which can be found in <a href="/wiki/Andrey_Terekhov" title="Andrey Terekhov">Andrey Terekhov</a>'s 2014 paper: "ALGOL 68 and Its Impact on the USSR and Russian Programming",<a href="#cite_note-15">[15]</a> and "Алгол 68 и его влияние на программирование в СССР и России".<a href="#cite_note-16">[16]</a> <a href="/wiki/Steve_Bourne" class="mw-redirect" title="Steve Bourne">Steve Bourne</a>, who was on the ALGOL 68 revision committee, took some of its ideas to his <a href="/wiki/Bourne_shell" title="Bourne shell">Bourne shell</a> (and thereby, to descendant <a href="/wiki/Unix_shell" title="Unix shell">Unix shells</a> such as <a href="/wiki/Bash_(Unix_shell)" title="Bash (Unix shell)">Bash</a>) and to <a href="/wiki/C_(programming_language)" title="C (programming language)">C</a> (and thereby to descendants such as <a href="/wiki/C%2B%2B" title="C++">C++</a>). The complete history of the project can be found in <a href="/wiki/Charles_H._Lindsey" title="Charles H. Lindsey">C. H. Lindsey</a>'s A History of ALGOL 68.<a href="#cite_note-FOOTNOTELindsey1996-17">[17]</a><a href="#cite_note-ahoa68-18">[18]</a> For a full-length treatment of the language, see "Programming ALGOL 68 Made Easy"<a href="#cite_note-19">[19]</a> by Dr. Sian Mountbatten, or "Learning ALGOL 68 Genie"<a href="#cite_note-20">[20]</a> by Marcel van der Veer which includes the Revised Report. <div class="mw-heading mw-heading2"><h2 id="History">History</h2>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=2" title="Edit section: History">edit</a>]</div> <div class="mw-heading mw-heading3"><h3 id="Origins">Origins</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=3" title="Edit section: Origins">edit</a>]</div> ALGOL 68, as the name implies, is a follow-on to the <a href="/wiki/ALGOL" title="ALGOL">ALGOL</a> language that was first formalized in 1960. That same year the <a href="/wiki/International_Federation_for_Information_Processing" title="International Federation for Information Processing">International Federation for Information Processing</a> (IFIP) formed and started the Working Group on ALGOL, or WG2.1. This group released an updated ALGOL 60 specification in Rome in April 1962. At a follow-up meeting in March 1964, it was agreed that the group should begin work on two follow-on standards, <a href="/wiki/ALGOL_X" title="ALGOL X">ALGOL X</a> which would be a redefinition of the language with some additions, and an <a href="/wiki/ALGOL_Y" title="ALGOL Y">ALGOL Y</a>, which would have the ability to modify its own programs in the style of the language <a href="/wiki/Lisp_(programming_language)" title="Lisp (programming language)">LISP</a>.<a href="#cite_note-FOOTNOTELindsey19937-21">[21]</a> <div class="mw-heading mw-heading3"><h3 id="Definition_process">Definition process</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=4" title="Edit section: Definition process">edit</a>]</div> The first meeting of the ALGOL X group was held in <a href="/wiki/Princeton_University" title="Princeton University">Princeton University</a> in May 1965. A report of the meeting noted two broadly supported themes, the introduction of <a href="/wiki/Strong_typing" class="mw-redirect" title="Strong typing">strong typing</a> and interest in <a href="/wiki/Euler_programming_language" class="mw-redirect" title="Euler programming language">Euler's</a> concepts of 'trees' or 'lists' for handling collections.<a href="#cite_note-FOOTNOTELindsey19939-22">[22]</a> At the second meeting in October in France, three formal proposals were presented, <a href="/wiki/Niklaus_Wirth" title="Niklaus Wirth">Niklaus Wirth</a>'s <a href="/wiki/ALGOL_W" title="ALGOL W">ALGOL W</a> along with comments about record structures by <a href="/wiki/C.A.R._Hoare" class="mw-redirect" title="C.A.R. Hoare">C.A.R. (Tony) Hoare</a>, a similar language by Gerhard Seegmüller, and a paper by <a href="/wiki/Adriaan_van_Wijngaarden" title="Adriaan van Wijngaarden">Adriaan van Wijngaarden</a> on "Orthogonal design and description of a formal language". The latter, written in almost indecipherable "W-Grammar", proved to be a decisive shift in the evolution of the language. The meeting closed with an agreement that van Wijngaarden would re-write the Wirth/Hoare submission using his W-Grammar.<a href="#cite_note-FOOTNOTELindsey19939-22">[22]</a> This seemingly simple task ultimately proved more difficult than expected, and the follow-up meeting had to be delayed six months. When it met in April 1966 in <a href="/wiki/Kootwijk" title="Kootwijk">Kootwijk</a>, van Wijngaarden's draft remained incomplete and Wirth and Hoare presented a version using more traditional descriptions. It was generally agreed that their paper was "the right language in the wrong formalism".<a href="#cite_note-FOOTNOTELindsey199324-23">[23]</a> As these approaches were explored, it became clear there was a difference in the way parameters were described that would have real-world effects, and while Wirth and Hoare protested that further delays might become endless, the committee decided to wait for van Wijngaarden's version. Wirth then implemented their current definition as ALGOL W.<a href="#cite_note-FOOTNOTELindsey199310-24">[24]</a> At the next meeting in <a href="/wiki/Warsaw" title="Warsaw">Warsaw</a> in October 1966,<a href="#cite_note-25">[25]</a> there was an initial report from the I/O Subcommittee who had met at the <a href="/wiki/Oak_Ridge_National_Laboratory" title="Oak Ridge National Laboratory">Oak Ridge National Laboratory</a> and the <a href="/wiki/University_of_Illinois" class="mw-redirect" title="University of Illinois">University of Illinois</a> but had not yet made much progress. The two proposals from the previous meeting were again explored, and this time a new debate emerged about the use of <a href="/wiki/Pointer_(computer_science)" class="mw-redirect" title="Pointer (computer science)">pointers</a>; ALGOL W used them only to refer to records, while van Wijngaarden's version could point to any object. To add confusion, <a href="/wiki/John_McCarthy_(computer_scientist)" title="John McCarthy (computer scientist)">John McCarthy</a> presented a new proposal for <a href="/wiki/Operator_overloading" title="Operator overloading">operator overloading</a> and the ability to string together and or constructs, and <a href="/wiki/Klaus_Samelson" title="Klaus Samelson">Klaus Samelson</a> wanted to allow <a href="/wiki/Anonymous_function" title="Anonymous function">anonymous functions</a>. In the resulting confusion, there was some discussion of abandoning the entire effort.<a href="#cite_note-FOOTNOTELindsey199310-24">[24]</a> The confusion continued through what was supposed to be the ALGOL Y meeting in <a href="/wiki/Zandvoort" title="Zandvoort">Zandvoort</a> in May 1967.<a href="#cite_note-FOOTNOTELindsey19939-22">[22]</a> <div class="mw-heading mw-heading3"><h3 id="Publication">Publication</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=5" title="Edit section: Publication">edit</a>]</div> A draft report was finally published in February 1968. This was met by "shock, horror and dissent",<a href="#cite_note-FOOTNOTELindsey19939-22">[22]</a> mostly due to the hundreds of pages of unreadable grammar and odd terminology. <a href="/wiki/Charles_H._Lindsey" title="Charles H. Lindsey">Charles H. Lindsey</a> attempted to figure out what "language was hidden inside of it",<a href="#cite_note-FOOTNOTELindsey199312-26">[26]</a> a process that took six man-weeks of effort. The resulting paper, "ALGOL 68 with fewer tears",<a href="#cite_note-27">[27]</a> was widely circulated. At a wider information processing meeting in <a href="/wiki/Z%C3%BCrich" class="mw-redirect" title="Zürich">Zürich</a> in May 1968, attendees complained that the language was being forced upon them and that IFIP was "the true villain of this unreasonable situation" as the meetings were mostly closed and there was no formal feedback mechanism. Wirth and <a href="/wiki/Peter_Naur" title="Peter Naur">Peter Naur</a> formally resigned their authorship positions in WG2.1 at that time.<a href="#cite_note-FOOTNOTELindsey199312-26">[26]</a> The next WG2.1 meeting took place in <a href="/wiki/Tirrenia" title="Tirrenia">Tirrenia</a> in June 1968. It was supposed to discuss the release of compilers and other issues, but instead devolved into a discussion on the language. van Wijngaarden responded by saying (or threatening) that he would release only one more version of the report. By this point Naur, Hoare, and Wirth had left the effort, and several more were threatening to do so.<a href="#cite_note-FOOTNOTELindsey199313-28">[28]</a> Several more meetings followed, <a href="/wiki/North_Berwick" title="North Berwick">North Berwick</a> in August 1968, Munich in December which produced the release of the official Report in January 1969 but also resulted in a contentious Minority Report being written. Finally, at <a href="/wiki/Banff,_Alberta" title="Banff, Alberta">Banff, Alberta</a> in September 1969, the project was generally considered complete and the discussion was primarily on errata and a greatly expanded Introduction to the Report.<a href="#cite_note-FOOTNOTELindsey199315-29">[29]</a> The effort took five years, burned out many of the greatest names in <a href="/wiki/Computer_science" title="Computer science">computer science</a>, and on several occasions became deadlocked over issues both in the definition and the group as a whole. Hoare released a "Critique of ALGOL 68" almost immediately,<a href="#cite_note-30">[30]</a> which has been widely referenced in many works. Wirth went on to further develop the ALGOL W concept and released this as Pascal in 1970. <div class="mw-heading mw-heading3"><h3 id="Implementations">Implementations</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=6" title="Edit section: Implementations">edit</a>]</div> <div class="mw-heading mw-heading4"><h4 id="ALGOL_68-R">ALGOL 68-R</h4>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=7" title="Edit section: ALGOL 68-R">edit</a>]</div> The first implementation of the standard, based on the late-1968 draft Report, was introduced by the <a href="/wiki/Royal_Radar_Establishment" title="Royal Radar Establishment">Royal Radar Establishment</a> in the UK as <a href="/wiki/ALGOL_68-R" title="ALGOL 68-R">ALGOL 68-R</a> in July 1970. This was, however, a subset of the full language, and <a href="/wiki/Barry_Mailloux" class="mw-redirect" title="Barry Mailloux">Barry Mailloux</a>, the final editor of the Report, joked that "It is a question of morality. We have a Bible and you are sinning!"<a href="#cite_note-implement-31">[31]</a> This version nevertheless became very popular on the <a href="/wiki/International_Computers_Limited" title="International Computers Limited">ICL</a> machines, and became a widely-used language in military coding, especially in the UK.<a href="#cite_note-shorter-32">[32]</a> Among the changes in 68-R was the requirement for all variables to be declared before their first use. This had a significant advantage that it allowed the compiler to be one-pass, as space for the variables in the <a href="/wiki/Activation_record" class="mw-redirect" title="Activation record">activation record</a> was set aside before it was used. However, this change also had the side-effect of demanding the PROCs be declared twice, once as a declaration of the types, and then again as the body of code. Another change was to eliminate the assumed VOID mode, an expression that returns no value (named a statement in other languages) and demanding the word VOID be added where it would have been assumed. Further, 68-R eliminated the explicit <a href="/wiki/Parallel_computing" title="Parallel computing">parallel processing</a> commands based on PAR.<a href="#cite_note-implement-31">[31]</a> <div class="mw-heading mw-heading4"><h4 id="Others">Others</h4>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=8" title="Edit section: Others">edit</a>]</div> The first full implementation of the language was introduced in 1974 by CDC Netherlands for the <a href="/wiki/Control_Data" class="mw-redirect" title="Control Data">Control Data</a> mainframe series. This saw limited use, mostly teaching in Germany and the Netherlands.<a href="#cite_note-shorter-32">[32]</a> A version similar to 68-R was introduced from <a href="/wiki/Carnegie_Mellon_University" title="Carnegie Mellon University">Carnegie Mellon University</a> in 1976 as 68S, and was again a one-pass compiler based on various simplifications of the original and intended for use on smaller machines like the <a href="/wiki/DEC_PDP-11" class="mw-redirect" title="DEC PDP-11">DEC PDP-11</a>. It too was used mostly for teaching purposes.<a href="#cite_note-shorter-32">[32]</a> A version for <a href="/wiki/IBM" title="IBM">IBM</a> mainframes did not become available until 1978, when one was released from <a href="/wiki/Cambridge_University" class="mw-redirect" title="Cambridge University">Cambridge University</a>. This was "nearly complete". Lindsey released a version for small machines including the <a href="/wiki/IBM_PC" class="mw-redirect" title="IBM PC">IBM PC</a> in 1984.<a href="#cite_note-shorter-32">[32]</a> Three open source Algol 68 implementations are known:<a href="#cite_note-33">[33]</a> <ul><li>a68g, <a href="/wiki/GPLv3" class="mw-redirect" title="GPLv3">GPLv3</a>, written by Marcel van der Veer.</li> <li>algol68toc, an <a href="/wiki/Open-source_software" title="Open-source software">open-source software</a> port of <a href="/wiki/ALGOL_68RS" title="ALGOL 68RS">ALGOL 68RS</a>.</li> <li>experimental Algol68 frontend for <a href="/wiki/GNU_Compiler_Collection" title="GNU Compiler Collection">GCC</a>, written by Jose E. Marchesi.<a href="#cite_note-34">[34]</a></li></ul> <div class="mw-heading mw-heading3"><h3 id="Timeline">Timeline</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=9" title="Edit section: Timeline">edit</a>]</div> <table class="wikitable"> <tbody><tr> <th scope="col">Year</th> <th scope="col">Event</th> <th scope="col">Contributor </th></tr> <tr> <td style="text-align:right;">March 1959</td> <td><a href="/wiki/ALGOL_Bulletin" title="ALGOL Bulletin">ALGOL Bulletin</a> Issue 1 (First)</td> <td><a href="/wiki/Peter_Naur" title="Peter Naur">Peter Naur</a> / <a href="/wiki/Association_for_Computing_Machinery" title="Association for Computing Machinery">ACM</a> </td></tr> <tr> <td style="text-align:right;">February 1968</td> <td>Draft Report(DR) Published<a href="#cite_note-35">[35]</a></td> <td><a href="/wiki/IFIP" class="mw-redirect" title="IFIP">IFIP</a> <a href="/wiki/IFIP_Working_Group_2.1" title="IFIP Working Group 2.1">Working Group 2.1</a> </td></tr> <tr> <td style="text-align:right;">March 1968</td> <td>Algol 68 Final Report<a href="#The_language_of_the_unrevised_report">r0</a> Presented at Munich Meeting</td> <td>IFIP Working Group 2.1 </td></tr> <tr> <td style="text-align:right;">June 1968</td> <td>Meeting in Tirrenia, Italy</td> <td>IFIP Working Group 2.1 </td></tr> <tr> <td style="text-align:right;">Aug 1968</td> <td>Meeting in North Berwick, Scotland</td> <td>IFIP Working Group 2.1 </td></tr> <tr> <td style="text-align:right;">December 1968</td> <td>ALGOL 68 Final Report<a href="#The_language_of_the_unrevised_report">r0</a> Presented at Munich Meeting</td> <td>IFIP Working Group 2.1 </td></tr> <tr> <td style="text-align:right;">April 1970</td> <td><a href="/wiki/ALGOL_68-R" title="ALGOL 68-R">ALGOL 68-R</a> under <a href="/wiki/GEORGE_(operating_system)" title="GEORGE (operating system)">GEORGE 3</a> on an <a href="/wiki/International_Computers_Limited" title="International Computers Limited">ICL</a> <a href="/wiki/ICT_1900_series" title="ICT 1900 series">1907F</a></td> <td><a href="/wiki/RSRE" class="mw-redirect" title="RSRE">Royal Signals and Radar Est.</a> </td></tr> <tr> <td style="text-align:right;">July 1970</td> <td>ALGOL 68 for the <a href="/wiki/Dartmouth_Time-Sharing_System" title="Dartmouth Time-Sharing System">Dartmouth Time-Sharing System</a><a href="#cite_note-36">[36]</a><a href="#cite_note-37">[37]</a></td> <td>Sidney Marshall </td></tr> <tr> <td style="text-align:right;">September 1973</td> <td>Algol 68 Revised Report<a href="#cite_note-38">[38]</a><a href="#Revisions">r1</a> Published</td> <td>IFIP Working Group 2.1 </td></tr> <tr> <td style="text-align:right;">1975</td> <td><a href="/wiki/ALGOL_68C" title="ALGOL 68C">ALGOL 68C</a>(C) – transportable compiler (zcode <a href="/wiki/Virtual_machine" title="Virtual machine">VM</a>)</td> <td><a href="/wiki/Stephen_R._Bourne" title="Stephen R. Bourne">S. Bourne</a>, <a href="/w/index.php?title=Andrew_Birrell&action=edit&redlink=1" class="new" title="Andrew Birrell (page does not exist)">Andrew Birrell</a>, and <a href="/wiki/Michael_Guy_(computer_scientist)" class="mw-redirect" title="Michael Guy (computer scientist)">Michael Guy</a> </td></tr> <tr> <td style="text-align:right;">June 1975</td> <td>G. E. Hedrick and Alan Robertson. The Oklahoma State ALGOL 68 Subset Compiler. 1975 International Conference on ALGOL 68. </td></tr> <tr> <td style="text-align:right;">June 1977</td> <td>Strathclyde ALGOL 68 conference, Scotland</td> <td>ACM </td></tr> <tr> <td style="text-align:right;">May 1978</td> <td>Proposals for ALGOL H – A Superlanguage of ALGOL 68<a href="#cite_note-39">[39]</a></td> <td>A. P. Black, V. J. Rayward-Smith </td></tr> <tr> <td style="text-align:right;">1984</td> <td>Full <a href="/wiki/ALGOL_68S" title="ALGOL 68S">ALGOL 68S</a>(S) compiler for Sun, SPARC, and PCs</td> <td>C. H. Lindsey et al, Manchester </td></tr> <tr> <td style="text-align:right;">August 1988</td> <td><a href="/wiki/ALGOL_Bulletin" title="ALGOL Bulletin">ALGOL Bulletin</a> Issue 52 (last)</td> <td>Ed. C. H. Lindsey / ACM </td></tr> <tr> <td style="text-align:right;">May 1997</td> <td>Algol68 S(S) published on the internet<a href="#cite_note-40">[40]</a></td> <td><a href="/wiki/Charles_H._Lindsey" title="Charles H. Lindsey">Charles H. Lindsey</a> </td></tr> <tr> <td style="text-align:right;">November 2001</td> <td>Algol 68 Genie(G) published on the internet<a href="#cite_note-41">[41]</a> (GNU GPL open source licensing)</td> <td>Marcel van der Veer </td></tr></tbody></table> <ul><li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20071217203826/http://npt.cc.rsu.ru/user/wanderer/ODP/ALGOL68.txt">"A Shorter History of Algol 68"</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20110514113912/http://hopl.murdoch.edu.au/showlanguage.prx?exp=311">ALGOL 68 – 3rd generation ALGOL</a></li></ul> <div class="mw-heading mw-heading3"><h3 id="The_Algorithmic_Language_ALGOL_68_Reports_and_Working_Group_members">The Algorithmic Language ALGOL 68 Reports and Working Group members</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=10" title="Edit section: The Algorithmic Language ALGOL 68 Reports and Working Group members">edit</a>]</div> <ul><li>March 1968: Draft Report on the Algorithmic Language ALGOL 68<a href="#cite_note-a68r-1-42">[42]</a> – Edited by: <a href="/wiki/Adriaan_van_Wijngaarden" title="Adriaan van Wijngaarden">Adriaan van Wijngaarden</a>, <a href="/wiki/Barry_J._Mailloux" title="Barry J. Mailloux">Barry J. Mailloux</a>, <a href="/wiki/John_E._L._Peck" title="John E. L. Peck">John Peck</a> and <a href="/wiki/Cornelis_H._A._Koster" title="Cornelis H. A. Koster">Cornelis H. A. Koster</a>.</li></ul> <style data-mw-deduplicate="TemplateStyles:r1023981488">@media all and (max-width:720px){.mw-parser-output .rquote{width:auto!important;float:none!important}}</style><style data-mw-deduplicate="TemplateStyles:r1244412712">.mw-parser-output .templatequote{overflow:hidden;margin:1em 0;padding:0 32px}.mw-parser-output .templatequotecite{line-height:1.5em;text-align:left;margin-top:0}@media(min-width:500px){.mw-parser-output .templatequotecite{padding-left:1.6em}}</style><blockquote class="templatequote rquote" style="float: right; width: 33%;">"Van Wijngaarden once characterized the four authors, somewhat tongue-in-cheek, as: Koster: <a href="#transput:_Input_and_output">transputter</a>, Peck: syntaxer, Mailloux: implementer, Van Wijngaarden: party ideologist." – Koster.</blockquote> <ul><li>October 1968: Penultimate Draft Report on the Algorithmic Language ALGOL 68 — Chapters 1-9<a href="#cite_note-a68r-1-9-43">[43]</a> Chapters 10-12<a href="#cite_note-a68r-10-12-44">[44]</a> — Edited by: A. van Wijngaarden, B.J. Mailloux, J. E. L. Peck and C. H. A. Koster.</li> <li>December 1968: Report on the Algorithmic Language ALGOL 68 — Offprint from Numerische Mathematik, 14, 79-218 (1969); Springer-Verlag.<a href="#cite_note-a68r0-kleine-45">[45]</a> — Edited by: A. van Wijngaarden, B. J. Mailloux, J. E. L. Peck and C. H. A. Koster.</li> <li>March 1970: Minority report, ALGOL Bulletin AB31.1.1 — signed by <a href="/wiki/Edsger_Dijkstra" class="mw-redirect" title="Edsger Dijkstra">Edsger Dijkstra</a>, <a href="/w/index.php?title=Fraser_Duncan&action=edit&redlink=1" class="new" title="Fraser Duncan (page does not exist)">Fraser Duncan</a>, <a href="/w/index.php?title=Jan_Garwick&action=edit&redlink=1" class="new" title="Jan Garwick (page does not exist)">Jan Garwick</a>, <a href="/wiki/Tony_Hoare" title="Tony Hoare">Tony Hoare</a>, <a href="/wiki/Brian_Randell" title="Brian Randell">Brian Randell</a>, <a href="/w/index.php?title=Gerhard_Seegm%C3%BCller&action=edit&redlink=1" class="new" title="Gerhard Seegmüller (page does not exist)">Gerhard Seegmüller</a>, <a href="/w/index.php?title=W%C5%82adys%C5%82aw_M._Turski&action=edit&redlink=1" class="new" title="Władysław M. Turski (page does not exist)">Wlad Turski</a>, and <a href="/wiki/Mike_Woodger" title="Mike Woodger">Mike Woodger</a>.</li> <li>September 1973: Revised Report on the Algorithmic Language Algol 68 — Springer-Verlag 1976<a href="#cite_note-a68r1-html-46">[46]</a> — Edited by: A. van Wijngaarden, B. Mailloux, J. Peck, K. Koster, <a href="/wiki/Michel_Sintzoff" title="Michel Sintzoff">Michel Sintzoff</a>, <a href="/wiki/Charles_H._Lindsey" title="Charles H. Lindsey">Charles H. Lindsey</a>, <a href="/wiki/Lambert_Meertens" title="Lambert Meertens">Lambert Meertens</a> and <a href="/w/index.php?title=Richard_G._Fisker&action=edit&redlink=1" class="new" title="Richard G. Fisker (page does not exist)">Richard G. Fisker</a>.</li> <li>other WG 2.1 members active in ALGOL 68 design:<a href="#cite_note-ahoa68-18">[18]</a> <a href="/wiki/Friedrich_L._Bauer" title="Friedrich L. Bauer">Friedrich L. Bauer</a> • <a href="/w/index.php?title=Hans_Bekic&action=edit&redlink=1" class="new" title="Hans Bekic (page does not exist)">Hans Bekic</a> • <a href="https://de.wikipedia.org/wiki/Gerhard_Goos" class="extiw" title="de:Gerhard Goos">Gerhard Goos</a> • <a href="/w/index.php?title=Peter_Zilahy_Ingerman&action=edit&redlink=1" class="new" title="Peter Zilahy Ingerman (page does not exist)">Peter Zilahy Ingerman</a> • <a href="/wiki/Peter_Landin" title="Peter Landin">Peter Landin</a> • <a href="/wiki/John_McCarthy_(computer_scientist)" title="John McCarthy (computer scientist)">John McCarthy</a> • <a href="/w/index.php?title=Jack_N._Merner&action=edit&redlink=1" class="new" title="Jack N. Merner (page does not exist)">Jack Merner</a> • <a href="/wiki/Peter_Naur" title="Peter Naur">Peter Naur</a> • <a href="/w/index.php?title=Manfred_Paul&action=edit&redlink=1" class="new" title="Manfred Paul (page does not exist)">Manfred Paul</a> • <a href="/wiki/Willem_van_der_Poel" title="Willem van der Poel">Willem van der Poel</a> • <a href="/wiki/Douglas_T._Ross" title="Douglas T. Ross">Doug Ross</a> • <a href="/wiki/Klaus_Samelson" title="Klaus Samelson">Klaus Samelson</a> • <a href="/wiki/Niklaus_Wirth" title="Niklaus Wirth">Niklaus Wirth</a> • <a href="/wiki/Nobuo_Yoneda" title="Nobuo Yoneda">Nobuo Yoneda</a>.</li></ul> <div class="mw-heading mw-heading3"><h3 id="Timeline_of_standardization">Timeline of standardization</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=11" title="Edit section: Timeline of standardization">edit</a>]</div> 1968: On 20 December 1968, the "Final Report" (MR 101) was adopted by the Working Group, then subsequently approved by the General Assembly of <a href="/wiki/UNESCO" title="UNESCO">UNESCO</a>'s <a href="/wiki/IFIP" class="mw-redirect" title="IFIP">IFIP</a> for publication. Translations of the standard were made for <a href="/wiki/Russian_language" title="Russian language">Russian</a>, <a href="/wiki/German_language" title="German language">German</a>, <a href="/wiki/French_language" title="French language">French</a> and <a href="/wiki/Bulgarian_language" title="Bulgarian language">Bulgarian</a>, and then later <a href="/wiki/Japanese_language" title="Japanese language">Japanese</a> and <a href="/wiki/Chinese_language" title="Chinese language">Chinese</a>.<a href="#cite_note-abp33-47">[47]</a> The standard was also made available in <a href="/wiki/Braille" title="Braille">Braille</a>. 1984: <a href="/wiki/ISO/IEC_JTC_1#History" title="ISO/IEC JTC 1">TC 97</a> considered ALGOL 68 for standardisation as "New Work Item" TC97/N1642 <a rel="nofollow" class="external autonumber" href="http://www.open-std.org/JTC1/sc22/docs/docs0200.html">[2]</a><a rel="nofollow" class="external autonumber" href="http://std.dkuug.dk/JTC1/sc22/sc22arc1.txt">[3]</a>. West Germany, Belgium, Netherlands, USSR and Czechoslovakia willing to participate in preparing the standard but the USSR and Czechoslovakia "were not the right kinds of member of the right ISO committees"<a rel="nofollow" class="external autonumber" href="http://archive.computerhistory.org/resources/text/algol/algol_bulletin/A50/P1.HTM">[4]</a> and Algol 68's ISO standardisation stalled.<a rel="nofollow" class="external autonumber" href="http://www.open-std.org/jtc1/sc22/open/n0200.pdf">[5]</a> 1988: Subsequently ALGOL 68 became one of the <a href="/wiki/GOST" title="GOST">GOST</a> standards in Russia. <ul><li>GOST 27974-88 Programming language ALGOL 68 — Язык программирования АЛГОЛ 68<a href="#cite_note-a68ru-48">[48]</a></li> <li>GOST 27975-88 Programming language ALGOL 68 extended — Язык программирования АЛГОЛ 68 расширенный<a href="#cite_note-a68ruext-49">[49]</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Notable_language_elements">Notable language elements</h2>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=12" title="Edit section: Notable language elements">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1235681985"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1092331828"><div class="side-box metadata side-box-right contains-special-characters noprint selfref"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1126788409"> <div class="side-box-flex"> <div class="side-box-text plainlist">This article contains Unicode 6.0 "<a rel="nofollow" class="external text" href="https://www.unicode.org/charts/PDF/U2300.pdf">Miscellaneous Technical</a>" characters. Without proper <a href="/wiki/Unicode#External_links" title="Unicode">rendering support</a>, you may see <a href="/wiki/Specials_(Unicode_block)#Replacement_character" title="Specials (Unicode block)">question marks, boxes, or other symbols</a> instead of something like "₁₀" (<a rel="nofollow" class="external text" href="http://mailcom.com/unicode/DecimalExponent.ttf">Decimal Exponent Symbol U+23E8 TTF</a>).</div></div> </div> <div class="mw-heading mw-heading3"><h3 id="Bold_symbols_and_reserved_words">Bold symbols and reserved words</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=13" title="Edit section: Bold symbols and reserved words">edit</a>]</div> The standard language contains about sixty reserved words, typically bolded in print, and some with "brief symbol" equivalents: <pre>MODE, OP, PRIO, PROC, FLEX, HEAP, LOC, LONG, REF, SHORT, BITS, BOOL, BYTES, CHAR, COMPL, INT, REAL, SEMA, STRING, VOID, CHANNEL, FILE, FORMAT, STRUCT, UNION, AT "@", EITHER<a href="#The_language_of_the_unrevised_report">r0</a>, IS ":=:", ISNT IS NOT<a href="#The_language_of_the_unrevised_report">r0</a> ":/=:" ":≠:", OF "→"<a href="#The_language_of_the_unrevised_report">r0</a>, TRUE, FALSE, EMPTY, NIL "○", SKIP "~", CO "¢", COMMENT "¢", PR, PRAGMAT, CASE ~ IN ~ OUSE ~ IN ~ OUT ~ ESAC "( ~ | ~ |: ~ | ~ | ~ )", FOR ~ FROM ~ TO ~ BY ~ WHILE ~ DO ~ OD, IF ~ THEN ~ ELIF ~ THEN ~ ELSE ~ FI "( ~ | ~ |: ~ | ~ | ~ )", PAR BEGIN ~ END "( ~ )", GO TO, GOTO, EXIT "□"<a href="#The_language_of_the_unrevised_report">r0</a>. </pre> <div class="mw-heading mw-heading3"><h3 id="Units:_Expressions">Units: Expressions</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=14" title="Edit section: Units: Expressions">edit</a>]</div> The basic language construct is the unit. A unit may be a formula, an enclosed clause, a routine text or one of several technically needed constructs (assignation, jump, skip, nihil). The technical term enclosed clause unifies some of the inherently bracketing constructs known as block, do statement, switch statement in other contemporary languages. When keywords are used, generally the reversed character sequence of the introducing keyword is used for terminating the enclosure, e.g. ( IF ~ THEN ~ ELSE ~ FI, CASE ~ IN ~ OUT ~ ESAC, FOR ~ WHILE ~ DO ~ OD ). This <a href="/wiki/Guarded_Command_Language#Selection:_if" title="Guarded Command Language">Guarded Command</a> syntax was reused by <a href="/wiki/Stephen_R._Bourne" title="Stephen R. Bourne">Stephen Bourne</a> in the common <a href="/wiki/Unix" title="Unix">Unix</a> <a href="/wiki/Bourne_shell" title="Bourne shell">Bourne shell</a>. An expression may also yield a multiple value, which is constructed from other values by a collateral clause. This construct just looks like the parameter pack of a procedure call. <div class="mw-heading mw-heading3"><h3 id="mode:_Declarations">mode: Declarations</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=15" title="Edit section: mode: Declarations">edit</a>]</div> The basic <a href="/wiki/Data_type" title="Data type">data types</a> (called <code>mode</code>s in Algol 68 parlance) are <code>real</code>, <code>int</code>, <code>compl</code> (<a href="/wiki/Complex_number" title="Complex number">complex number</a>), <code>bool</code>, <code>char</code>, <code>bits</code> and <code>bytes</code>. For example: <pre>INT n = 2; CO n is fixed as a constant of 2. CO INT m := 3; CO m is a newly created local variable whose value is initially set to 3. CO CO This is short for ref int m = loc int := 3; CO REAL avogadro = 6.0221415⏨23; CO Avogadro number CO long long real long long pi = 3.14159 26535 89793 23846 26433 83279 50288 41971 69399 37510; COMPL square root of minus one = 0 ⊥ 1; </pre> However, the declaration <code>REAL x;</code> is just <a href="/wiki/Syntactic_sugar" title="Syntactic sugar">syntactic sugar</a> for <code>REF REAL x = LOC REAL;</code>. That is, <code>x</code> is really the constant identifier for a reference to a newly generated local REAL variable. Furthermore, instead of defining both <code>float</code> and <code>double</code>, or <code>int</code> and <code>long</code> and <code>short</code>, etc., ALGOL 68 provides modifiers, so that the presently common <code>double</code> would be written as LONG REAL or LONG LONG REAL instead, for example. The prelude constants <code>max real</code> and <code>min long int</code> are provided to adapt programs to different implementations. All variables need to be declared, but declaration does not have to precede the first use. primitive-declarer: INT, REAL, COMPL, COMPLEXG, BOOL, CHAR, STRING, BITS, BYTES, FORMAT, FILE, PIPEG, CHANNEL, SEMA <ul><li>BITS – a "packed vector" of BOOL.</li> <li>BYTES – a "packed vector" of CHAR.</li> <li>STRING – a FLEXible array of CHAR.</li> <li>SEMA – a <a href="/wiki/Semaphore_(programming)" title="Semaphore (programming)">SEMAphore</a> which can be initialised with the OPerator LEVEL.</li></ul> Complex types can be created from simpler ones using various type constructors: <ul><li>REF mode – a reference to a value of type mode, similar to & in C/C++ and REF in Pascal</li> <li>STRUCT – used to build structures, like STRUCT in C/C++ and RECORD in Pascal</li> <li>UNION – used to build unions, like in C/C++ and Pascal</li> <li>PROC – used to specify procedures, like functions in C/C++ and procedures/functions in Pascal</li></ul> For some examples, see <a href="/wiki/Comparison_of_ALGOL_68_and_C%2B%2B" title="Comparison of ALGOL 68 and C++">Comparison of ALGOL 68 and C++</a>. Other declaration symbols include: FLEX, HEAP, LOC, REF, LONG, SHORT, EVENTS <ul><li>FLEX – declare the array to be flexible, i.e. it can grow in length on demand.</li> <li>HEAP – allocate variable some free space from the global heap.</li> <li>LOC – allocate variable some free space of the local stack.</li> <li>LONG – declare an INT, REAL or COMPL to be of a LONGer size.</li> <li>SHORT – declare an INT, REAL or COMPL to be of a SHORTer size.</li></ul> A name for a mode (type) can be declared using a MODE declaration, which is similar to TYPEDEF in C/C++ and TYPE in Pascal: <pre> INT max=99; MODE newmode = [0:9][0:max]STRUCT ( LONG REAL a, b, c, SHORT INT i, j, k, REF REAL r ); </pre> This is similar to the following C code: <div class="mw-highlight mw-highlight-lang-c mw-content-ltr" dir="ltr"><pre> const int max=99; typedef struct { double a, b, c; short i, j, k; float *r; } newmode[9+1][max+1]; </pre></div> For ALGOL 68, only the NEWMODE mode-indication appears to the left of the equals symbol, and most notably the construction is made, and can be read, from left to right without regard to priorities. Also, the lower bound of Algol 68 arrays is one by default, but can be any integer from -max int to max int. Mode declarations allow types to be <a href="/wiki/Recursive_data_type" title="Recursive data type">recursive</a>: defined directly or indirectly in terms of themselves. This is subject to some restrictions – for instance, these declarations are illegal: <pre> MODE A = REF A MODE A = STRUCT (A a, B b) MODE A = PROC (A a) A </pre> while these are valid: <pre> MODE A = STRUCT (REF A a, B b) MODE A = PROC (REF A a) REF A </pre> <div class="mw-heading mw-heading3"><h3 id="Coercions:_casting">Coercions: casting</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=16" title="Edit section: Coercions: casting">edit</a>]</div> The <a href="/wiki/Implicit_type_conversion" class="mw-redirect" title="Implicit type conversion">coercions</a> produce a coercee from a coercend according to three criteria: the a priori mode of the coercend before the application of any coercion, the a posteriori mode of the coercee required after those coercions, and the syntactic position or "sort" of the coercee. Coercions may be cascaded. The six possible coercions are termed deproceduring, dereferencing, uniting, widening, rowing, and voiding. Each coercion, except for uniting, prescribes a corresponding dynamic effect on the associated values. Hence, many primitive actions can be programmed implicitly by coercions. Context strength – allowed coercions: <ul><li>soft – deproceduring</li> <li>weak – dereferencing or deproceduring, yielding a name</li> <li>meek – dereferencing or deproceduring</li> <li>firm – meek, followed by uniting</li> <li>strong – firm, followed by widening, rowing or voiding</li></ul> <div class="mw-heading mw-heading4"><h4 id="Coercion_hierarchy_with_examples">Coercion hierarchy with examples</h4>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=17" title="Edit section: Coercion hierarchy with examples">edit</a>]</div> ALGOL 68 has a hierarchy of contexts which determine the kind of coercions available at a particular point in the program. These contexts are: <table class="wikitable"> <tbody><tr> <th rowspan="2" class="nowrap ts-vertical-header is-valign-middle" style=""><div style=""><style data-mw-deduplicate="TemplateStyles:r1221560606">@supports(writing-mode:vertical-rl){.mw-parser-output .ts-vertical-header{line-height:1;max-width:1em;padding:0.4em;vertical-align:bottom;width:1em}html.client-js .mw-parser-output .sortable:not(.jquery-tablesorter) .ts-vertical-header:not(.unsortable),html.client-js .mw-parser-output .ts-vertical-header.headerSort{background-position:50%.4em;padding-right:0.4em;padding-top:21px}.mw-parser-output .ts-vertical-header.is-valign-top{vertical-align:top}.mw-parser-output .ts-vertical-header.is-valign-middle{vertical-align:middle}.mw-parser-output .ts-vertical-header.is-normal{font-weight:normal}.mw-parser-output .ts-vertical-header>*{display:inline-block;transform:rotate(180deg);writing-mode:vertical-rl}@supports(writing-mode:sideways-lr){.mw-parser-output .ts-vertical-header>*{transform:none;writing-mode:sideways-lr}}}</style>Context</div> </th> <th rowspan="2">Context location </th> <th colspan="5">Coercions available </th> <th rowspan="2">Coercion examples in the context </th></tr> <tr style="text-align:center"> <td bgcolor="#5555ff" style="" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">Soft</div> </td> <td bgcolor="#00ee00" style="" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">Weak</div> </td> <td bgcolor="#dddd00" style="" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">Meek</div> </td> <td bgcolor="#cc8800" style="" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">Firm</div> </td> <td bgcolor="#bb0000" style="" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">Strong</div> </td></tr> <tr> <td bgcolor="#bb0000" style="" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">Strong</div> </td> <td>Right hand side of: <ul><li>Identity-declarations, as "~" in: <code>REAL x = ~</code></li> <li>Initialisations, as "~" in: <code>REAL x := ~</code></li></ul> Also: <ul><li>Actual-parameters of calls, as "~" in:<code>PROC: sin(~)</code></li> <li>Enclosed clauses of casts, as "~" in: <code>REAL(~)</code></li> <li>Units of routine-texts</li> <li>Statements yielding VOID</li> <li>All parts (but one) of a balanced clause</li> <li>One side of an identity relation, as "~" in: <code> ~ IS ~</code></li></ul> </td> <td bgcolor="#5555ff" style="" rowspan="4" width="50px" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606"> deproceduring</div> </td> <td bgcolor="#00ee00" style="" rowspan="3" width="50px" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606"> All SOFT then weak dereferencing (dereferencing or deproceduring, yielding a name)</div> </td> <td bgcolor="#dddd00" style="" rowspan="2" width="50px" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">All WEAK then dereferencing (dereferencing or deproceduring)</div> </td> <td bgcolor="#cc8800" style="" rowspan="1" width="50px" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606"> All MEEK then uniting</div> </td> <td bgcolor="#bb0000" style="" width="50px" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606"> All FIRM then widening, rowing or voiding</div> </td> <td colspan="1" bgcolor="#bb0000" style="color:#ffffff;"> Widening occurs if there is no loss of precision. For example: An INT will be coerced to a REAL, and a REAL will be coerced to a LONG REAL. But not vice versa. Examples: <ul><li>to LONG INT from INT</li> <li>to REAL from INT</li> <li>to COMPL from REAL</li> <li>to []BOOL from BITS</li> <li>to STRING from BYTES</li></ul> A variable can also be coerced (rowed) to an array of length 1. For example: <ul><li>to [1]INT from INT</li> <li>to [1]REAL from REAL etc.</li></ul> </td></tr> <tr> <td bgcolor="#cc8800" style="" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">Firm</div> </td> <td> <ul><li>Operands of formulas as "~" in:<code>~ OP ~</code></li> <li>Parameters of transput calls</li></ul> </td> <td colspan="3" bgcolor="#cc8800" style="color:#ffffff;">Example: <code>UNION(INT,REAL) var := 1</code> </td></tr> <tr> <td bgcolor="#dddd00" style="" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">Meek</div> </td> <td> <ul><li>Trimscripts (yielding INT)</li> <li>Enquiries: e.g. as "~" in the following</li></ul> <code>IF ~ THEN ... FI</code> and <code>FROM ~ BY ~ TO ~ WHILE ~ DO ... OD etc</code> <ul><li>Primaries of calls (e.g. sin in sin(x))</li></ul> </td> <td colspan="4" bgcolor="#dddd00" style="color:#000000;">Examples: <ul><li>to BOOL from REF REF BOOL</li> <li>to INT from REF REF REF INT</li></ul> </td></tr> <tr> <td bgcolor="#00ee00" style="" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">Weak</div> </td> <td> <ul><li>Primaries of slices, as in "~" in: <code>~[1:99]</code></li> <li>Secondaries of selections, as "~" in: <code>value OF ~</code></li></ul> </td> <td colspan="5" bgcolor="#00ee00" style="color:#ffffff;">Examples: <ul><li>to REF INT from REF REF INT</li> <li>to REF REAL from REF REF REF REAL</li> <li>to REF STRUCT from REF REF REF REF STRUCT</li></ul> </td></tr> <tr> <td bgcolor="#5555ff" style="" class="nowrap ts-vertical-header is-valign-middle"><div style=""><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1221560606">Soft</div> </td> <td>The LHS of assignments, as "~" in: <code>~ := ...</code> </td> <td colspan="6" bgcolor="#5555ff" style="color:#ffffff;">Example: <ul><li>deproceduring of: <code>PROC REAL random: e.g. random</code></li></ul> </td></tr></tbody></table> For more details about Primaries, Secondaries, Tertiary & Quaternaries refer to <a href="#Dyadic_operators_with_associated_priorities">Operator precedence</a>. <div class="mw-heading mw-heading3"><h3 id="pr_&_co:_Pragmats_and_Comments">pr & co: Pragmats and Comments</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=18" title="Edit section: pr & co: Pragmats and Comments">edit</a>]</div> Pragmats are <a href="/wiki/Directive_(programming)" title="Directive (programming)">directives</a> in the program, typically hints to the compiler; in newer languages these are called "pragmas" (no 't'). e.g. <pre>PRAGMAT heap=32 PRAGMAT PR heap=32 PR </pre> Comments can be inserted in a variety of ways: <pre>¢ The original way of adding your 2 cents worth to a program ¢ COMMENT "bold" comment COMMENT CO Style i comment CO # Style ii comment # £ This is a hash/pound comment for a UK keyboard £ </pre> Normally, comments cannot be nested in ALGOL 68. This restriction can be circumvented by using different comment delimiters (e.g. use hash only for temporary code deletions). <div class="mw-heading mw-heading3"><h3 id="Expressions_and_compound_statements">Expressions and compound statements</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=19" title="Edit section: Expressions and compound statements">edit</a>]</div> ALGOL 68 being an <a href="/wiki/Expression-oriented_programming_languages" class="mw-redirect" title="Expression-oriented programming languages">expression-oriented programming language</a>, the value returned by an <a href="/wiki/Assignment_(programming)" class="mw-redirect" title="Assignment (programming)">assignment</a> statement is a reference to the destination. Thus, the following is valid ALGOL 68 code: <pre> REAL half pi, one pi; one pi := 2 * ( half pi := 2 * arc tan(1) ) </pre> This notion is present in <a href="/wiki/C_(programming_language)" title="C (programming language)">C</a> and <a href="/wiki/Perl" title="Perl">Perl</a>, among others. Note that as in earlier languages such as <a href="/wiki/Algol_60" class="mw-redirect" title="Algol 60">Algol 60</a> and <a href="/wiki/FORTRAN" class="mw-redirect" title="FORTRAN">FORTRAN</a>, spaces are allowed in identifiers, so that <code>half pi</code> is a single identifier (thus avoiding the underscores versus <a href="/wiki/Camel_case_(programming)" class="mw-redirect" title="Camel case (programming)">camel case</a> versus all lower-case issues). As another example, to express the mathematical idea of a sum of <code>f(i)</code> from i=1 to n, the following ALGOL 68 integer expression suffices: <pre> (INT sum := 0; FOR i TO n DO sum +:= f(i) OD; sum) </pre> Note that, being an integer expression, the former block of code can be used in any context where an integer value can be used. A block of code returns the value of the last expression it evaluated; this idea is present in <a href="/wiki/Lisp_(programming_language)" title="Lisp (programming language)">Lisp</a>, among other languages. Compound statements are all terminated by distinctive closing brackets: <ul><li>IF choice clauses:</li></ul> <pre> IF condition THEN statements [ ELSE statements ] FI "brief" form: ( condition | statements | statements ) </pre> <pre> IF condition1 THEN statements ELIF condition2 THEN statements [ ELSE statements ] FI "brief" form: ( condition1 | statements |: condition2 | statements | statements ) </pre> This scheme not only avoids the <a href="/wiki/Dangling_else" title="Dangling else">dangling else</a> problem but also avoids having to use <code>BEGIN</code> and <code>END</code> in embedded <a href="/wiki/Statement_(programming)" class="mw-redirect" title="Statement (programming)">statement</a> sequences. <ul><li>CASE choice clauses:</li></ul> <pre> CASE switch IN statements, statements,... [ OUT statements ] ESAC "brief" form: ( switch | statements,statements,... | statements ) </pre> <pre> CASE switch1 IN statements, statements,... OUSE switch2 IN statements, statements,... [ OUT statements ] ESAC "brief" form of CASE statement: ( switch1 | statements,statements,... |: switch2 | statements,statements,... | statements ) </pre> Choice clause example with Brief symbols: <pre>PROC days in month = (INT year, month)INT: (month| 31, (year÷×4=0 ∧ year÷×100≠0 ∨ year÷×400=0 | 29 | 28 ), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ); </pre> Choice clause example with Bold symbols: <pre>PROC days in month = (INT year, month)INT: CASE month IN 31, IF year MOD 4 EQ 0 AND year MOD 100 NE 0 OR year MOD 400 EQ 0 THEN 29 ELSE 28 FI, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ESAC; </pre> Choice clause example mixing Bold and Brief symbols: <pre>PROC days in month = (INT year, month)INT: CASE month IN ¢Jan¢ 31, ¢Feb¢ ( year MOD 4 = 0 AND year MOD 100 ≠ 0 OR year MOD 400 = 0 | 29 | 28 ), ¢Mar¢ 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ¢ to Dec. ¢ ESAC; </pre> Algol68 allowed the switch to be of either type INT or (uniquely) UNION. The latter allows the enforcing <a href="/wiki/Strong_typing" class="mw-redirect" title="Strong typing">strong typing</a> onto UNION variables. c.f. <a href="#struct,_union_&_.5B:.5D:_Structures,_unions_and_arrays">union</a> below for example. <ul><li><a href="/wiki/For_loop" title="For loop">do</a> loop clause:</li></ul> <pre> [ FOR index ] [ FROM first ] [ BY increment ] [ TO last ] [ WHILE condition ] DO statements OD The minimum form of a "loop clause" is thus: DO statements OD </pre> This was considered the "universal" loop, the full syntax is: <pre>FOR i FROM 1 BY -22 TO -333 WHILE i×i≠4444 DO ~ OD </pre> The construct have several unusual aspects: <ul><li>only the DO ~ OD portion was compulsory, in which case the loop will iterate indefinitely.</li> <li>thus the clause TO 100 DO ~ OD, will iterate only 100 times.</li> <li>the WHILE "syntactic element" allowed a programmer to break from a FOR loop early. e.g.</li></ul> <pre>INT sum sq:=0; FOR i WHILE print(("So far:",i,newline)); sum sq≠70↑2 DO sum sq+:=i↑2 OD </pre> Subsequent "extensions" to the standard Algol68 allowed the TO syntactic element to be replaced with UPTO and DOWNTO to achieve a small optimisation. The same compilers also incorporated: <ul><li>UNTIL(C) – for late loop termination.</li> <li>FOREACH(S) – for working on arrays in <a href="/wiki/Parallel_computing" title="Parallel computing">parallel</a>.</li></ul> Further examples can be found in the code examples below. <div class="mw-heading mw-heading3"><h3 id="struct,_union_&_[:]:_Structures,_unions_and_arrays">struct, union & <code class="mw-highlight mw-highlight-lang-text mw-content-ltr" style="" dir="ltr">[:]</code>: Structures, unions and arrays</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=20" title="Edit section: struct, union & [:]: Structures, unions and arrays">edit</a>]</div> ALGOL 68 supports <a href="/wiki/Array_data_structure" class="mw-redirect" title="Array data structure">arrays</a> with any number of dimensions, and it allows for the slicing of whole or partial rows or columns. <pre> MODE VECTOR = [1:3] REAL; # vector MODE declaration (typedef) # MODE MATRIX = [1:3,1:3]REAL; # matrix MODE declaration (typedef) # VECTOR v1  := (1,2,3); # array variable initially (1,2,3) # []REAL v2 = (4,5,6); # constant array, type equivalent to VECTOR, bounds are implied # OP + = (VECTOR a,b) VECTOR: # binary OPerator definition # (VECTOR out; FOR i FROM ⌊a TO ⌈a DO out[i] := a[i]+b[i] OD; out); MATRIX m := (v1, v2, v1+v2); print ((m[,2:])); # a slice of the 2nd and 3rd columns # </pre> Matrices can be sliced either way, e.g.: <pre> REF VECTOR row = m[2,]; # define a REF (pointer) to the 2nd row # REF VECTOR col = m[,2]; # define a REF (pointer) to the 2nd column # </pre> ALGOL 68 supports multiple field structures (STRUCT) and <a href="/wiki/United_modes" class="mw-redirect" title="United modes">united modes</a>. Reference variables may point to any MODE including array slices and structure fields. For an example of all this, here is the traditional linked list declaration: <pre> MODE NODE = UNION (VOID, REAL, INT, COMPL, STRING), LIST = STRUCT (NODE val, REF LIST next); </pre> Usage example for UNION CASE of NODE: <table border="1" style="border-collapse:collapse; border:5px double gray; float:left;" class="wikitable"> <tbody><tr> <th>Algol68<a href="#The_language_of_the_unrevised_report">r0</a> as in the 1968 Final Report </th> <th>Algol68<a href="#Revisions">r1</a> as in the 1973 Revised Report </th></tr> <tr> <td> <pre> NODE n := "1234"; REAL r; INT i; COMPL c; STRING s CASE r,i,c,s::=n IN print(("real:", r)), print(("int:", i)), print(("compl:", c)), print(("string:", s)) OUT print(("?:", n)) ESAC </pre> </td> <td> <pre> NODE n := "1234"; # or n := EMPTY; # CASE n IN (VOID): print(("void:", "EMPTY")), (REAL r): print(("real:", r)), (INT i): print(("int:", i)), (COMPL c): print(("compl:", c)), (STRING s): print(("string:", s)) OUT print(("?:", n)) ESAC </pre> </td></tr></tbody></table> <div style="clear:both;" class=""></div> <div class="mw-heading mw-heading3"><h3 id="proc:_Procedures">proc: Procedures</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=21" title="Edit section: proc: Procedures">edit</a>]</div> Procedure (PROC) declarations require type specifications for both the parameters and the result (VOID if none): <pre> PROC max of real = (REAL a, b) REAL: IF a > b THEN a ELSE b FI; </pre> or, using the "brief" form of the conditional statement: <pre> PROC max of real = (REAL a, b) REAL: (a>b | a | b); </pre> The return value of a <code>proc</code> is the value of the last expression evaluated in the procedure. References to procedures (ref proc) are also permitted. <a href="/wiki/Call_by_reference" class="mw-redirect" title="Call by reference">Call-by-reference</a> parameters are provided by specifying references (such as <code>ref real</code>) in the formal argument list. The following example defines a procedure that applies a function (specified as a parameter) to each element of an array: <pre> PROC apply = (REF [] REAL a, PROC (REAL) REAL f):   FOR i FROM LWB a TO UPB a DO a[i] := f(a[i]) OD </pre> This simplicity of code was unachievable in ALGOL 68's predecessor <a href="/wiki/ALGOL_60" title="ALGOL 60">ALGOL 60</a>. <div class="mw-heading mw-heading3"><h3 id="op:_Operators">op: Operators</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=22" title="Edit section: op: Operators">edit</a>]</div> The programmer may define new <a href="/wiki/Operator_(programming)" class="mw-redirect" title="Operator (programming)">operators</a> and both those and the pre-defined ones may be <a href="/wiki/Overloading_(programming)" class="mw-redirect" title="Overloading (programming)">overloaded</a> and their priorities may be changed by the coder. The following example defines operator <code>MAX</code> with both dyadic and monadic versions (scanning across the elements of an array). <pre> PRIO MAX = 9;   OP MAX = (INT a,b) INT: ( a>b | a | b ); OP MAX = (REAL a,b) REAL: ( a>b | a | b ); OP MAX = (COMPL a,b) COMPL: ( ABS a > ABS b | a | b );   OP MAX = ([]REAL a) REAL: (REAL out := a[LWB a]; FOR i FROM LWB a + 1 TO UPB a DO ( a[i]>out | out:=a[i] ) OD; out) </pre> <div class="mw-heading mw-heading4"><h4 id="Array,_Procedure,_Dereference_and_coercion_operations">Array, Procedure, Dereference and coercion operations</h4>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=23" title="Edit section: Array, Procedure, Dereference and coercion operations">edit</a>]</div> <table class="wikitable"> <tbody><tr> <th style="background:#ccc;">PRIOrity </th> <th style="background:#ccc;">Operation <a href="#The_language_of_the_unrevised_report">r0</a>&<a href="#Revisions">r1</a> </th> <th style="background:#ccc;">+Algol68<a href="#The_language_of_the_unrevised_report">r0</a> </th> <th style="background:#ccc;">+Algol68G </th></tr> <tr> <td align="CENTER">Effectively 12 (Primary)</td> <td>dereferencing, deproceduring(~,~), subscripting[~], rowing[~,], slicing[~:~], size denotations LONG & SHORT </td> <td>proceduring </td> <td align="CENTER">currying(~,,,), DIAG, TRNSP, ROW, COL </td></tr> <tr> <td align="CENTER">Effectively 11 (Secondary)</td> <td>OF (selection), LOC & HEAP (generators) </td> <td>→ (selection) </td> <td>NEW (generators) </td></tr></tbody></table> These are technically not operators, rather they are considered "<a rel="nofollow" class="external text" href="https://web.archive.org/web/20130101062456/http://jmvdveer.home.xs4all.nl/report.html#52">units associated with names</a>" <div class="mw-heading mw-heading4"><h4 id="Monadic_operators">Monadic operators</h4>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=24" title="Edit section: Monadic operators">edit</a>]</div> <table class="wikitable"> <tbody><tr> <th style="background:#ccc;">PRIOrity (Tertiary) </th> <th style="background:#ccc;">Algol68 "Worthy characters<a class="external autonumber" href="https://en.wikipedia.org/wiki/ALGOL_68#endnote_worthy">[6]</a>"<a href="#The_language_of_the_unrevised_report">r0</a>&<a href="#Revisions">r1</a> </th> <th style="background:#ccc;">+Algol68<a href="#The_language_of_the_unrevised_report">r0</a>&<a href="#Revisions">r1</a> </th> <th style="background:#ccc;">+Algol68C,G </th> <th style="background:#ccc;">+Algol68<a href="#The_language_of_the_unrevised_report">r0</a> </th></tr> <tr> <td align="CENTER">10</td> <td>NOT ~, UP, DOWN, LWB, UPB, -, ABS, ARG, BIN, ENTIER, LENG, LEVEL, ODD, REPR, ROUND, SHORTEN </td> <td>¬, ↑, ↓, ⌊, ⌈ </td> <td>NORM, TRACE, T, DET, INV </td> <td>LWS, UPS, ⎩, ⎧, BTB, CTB </td></tr></tbody></table> <div class="mw-heading mw-heading4"><h4 id="Dyadic_operators_with_associated_priorities">Dyadic operators with associated priorities</h4>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=25" title="Edit section: Dyadic operators with associated priorities">edit</a>]</div> <table class="wikitable"> <tbody><tr> <th style="background:#ccc;">PRIOrity (Tertiary) </th> <th style="background:#ccc;">Algol68 "Worthy characters"<a href="#The_language_of_the_unrevised_report">r0</a>&<a href="#Revisions">r1</a> </th> <th style="background:#ccc;">+Algol68<a href="#The_language_of_the_unrevised_report">r0</a>&<a href="#Revisions">r1</a> </th> <th style="background:#ccc;">+Algol68C,G </th> <th style="background:#ccc;">+Algol68<a href="#The_language_of_the_unrevised_report">r0</a> </th></tr> <tr style="font-family:monospace"> <td align="CENTER">9</td> <td>+*, I</td> <td>+×, ⊥</td> <td></td> <td>! </td></tr> <tr style="font-family:monospace"> <td align="CENTER">8</td> <td>SHL, SHR, **, UP, DOWN, LWB, UPB</td> <td>↑, ↓, ⌊, ⌈</td> <td></td> <td>××, ^, LWS, UPS, ⎩, ⎧ </td></tr> <tr style="font-family:monospace"> <td align="CENTER">7</td> <td>*, /,  %, OVER,  %*, MOD, ELEM</td> <td>×, ÷, ÷×, ÷*, %×, □</td> <td></td> <td>÷: </td></tr> <tr style="font-family:monospace"> <td align="CENTER">6</td> <td>-, +</td> <td></td> <td></td> <td> </td></tr> <tr style="font-family:monospace"> <td align="CENTER">5</td> <td><, LT, <=, LE, >=, GE, >, GT</td> <td>≤, ≥</td> <td></td> <td> </td></tr> <tr style="font-family:monospace"> <td align="CENTER">4</td> <td>EQ =, NE ~= /=</td> <td>≠, ¬=</td> <td></td> <td> </td></tr> <tr style="font-family:monospace"> <td align="CENTER">3</td> <td>&, AND</td> <td>∧</td> <td></td> <td>/\ </td></tr> <tr style="font-family:monospace"> <td align="CENTER">2</td> <td>OR</td> <td>∨</td> <td></td> <td>\/ </td></tr> <tr style="font-family:monospace"> <td align="CENTER">1</td> <td>MINUSAB, PLUSAB, TIMESAB, DIVAB, OVERAB, MODAB, PLUSTO, -:=, +:=, *:=, /:=, %:=, %*:=, +=: </td> <td>×:=, ÷:=, ÷×:=, ÷*:=,  %×:=</td> <td></td> <td>MINUS, PLUS, DIV, OVERB, MODB, ÷::=, PRUS </td></tr></tbody></table> Specific details: <ul><li>Tertiaries include names NIL and ○.</li> <li>LWS: In Algol68<a href="#The_language_of_the_unrevised_report">r0</a> the operators LWS and ⎩ ... both return TRUE if the lower state of the dimension of an array is fixed.</li> <li>The UPS and ⎧ operators are similar on the upper state.</li> <li>The LWB and UPB operators are automatically available on UNIONs of different orders (and MODEs) of arrays. eg. UPB of <code class="mw-highlight mw-highlight-lang-text mw-content-ltr" style="" dir="ltr">union([]int, [,]real, flex[,,,]char)</code></li></ul> <div class="mw-heading mw-heading4"><h4 id="Assignation_and_identity_relations,_etc.">Assignation and identity relations, etc.</h4>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=26" title="Edit section: Assignation and identity relations, etc.">edit</a>]</div> These are technically not operators, rather they are considered "<a rel="nofollow" class="external text" href="https://web.archive.org/web/20130101062456/http://jmvdveer.home.xs4all.nl/report.html#052">units associated with names</a>" <table class="wikitable"> <tbody><tr> <th style="background:#ccc;">PRIOrity (Quaternaries) </th> <th style="background:#ccc;">Algol68 "Worthy characters"<a href="#The_language_of_the_unrevised_report">r0</a>&<a href="#Revisions">r1</a> </th> <th style="background:#ccc;">+Algol68<a href="#The_language_of_the_unrevised_report">r0</a>&<a href="#Revisions">r1</a> </th> <th style="background:#ccc;">+Algol68C,G,R </th> <th style="background:#ccc;">+Algol68<a href="#The_language_of_the_unrevised_report">r0</a> </th></tr> <tr> <td align="CENTER">Effectively 0</td> <td><style data-mw-deduplicate="TemplateStyles:r886049734">.mw-parser-output .monospaced{font-family:monospace,monospace}</style>:=, IS :=:, ISNT :/=: :~=:, AT @, ":", ";"</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">:≠: :¬=: </td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">:=:=C, =:=R</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">..=, .=, CT, ::, CTAB, ::=, .., is not, "..", ".," </td></tr></tbody></table> Note: Quaternaries include names SKIP and ~. <code class="mw-highlight mw-highlight-lang-text mw-content-ltr" style="" dir="ltr">:=:</code> (alternatively <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">IS) tests if two pointers are equal; <code class="mw-highlight mw-highlight-lang-text mw-content-ltr" style="" dir="ltr">:/=:</code> (alternatively <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">ISNT) tests if they are unequal. <div class="mw-heading mw-heading5"><h5 id="Why_:=:_and_:/=:_are_needed">Why <code class="mw-highlight mw-highlight-lang-text mw-content-ltr" style="" dir="ltr">:=:</code> and <code class="mw-highlight mw-highlight-lang-text mw-content-ltr" style="" dir="ltr">:/=:</code> are needed</h5>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=27" title="Edit section: Why :=: and :/=: are needed">edit</a>]</div> Consider trying to compare two pointer values, such as the following variables, declared as pointers-to-integer: <dl><dd><code>REF INT ip, jp </code></dd></dl> Now consider how to decide whether these two are pointing to the same location, or whether one of them is pointing to NIL. The following expression <dl><dd><code>ip = jp </code></dd></dl> will dereference both pointers down to values of type <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">INT, and compare those, since the = operator is defined for <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">INT, but not <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">REF INT. It is not legal to define = for operands of type <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">REF INT and <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">INT at the same time, because then calls become ambiguous, due to the implicit coercions that can be applied: should the operands be left as <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">REF INT and that version of the operator called? Or should they be dereferenced further to <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">INT and that version used instead? Therefore the following expression can never be made legal: <dl><dd><code>ip = NIL </code></dd></dl> Hence the need for separate constructs not subject to the normal coercion rules for operands to operators. But there is a gotcha. The following expressions: <dl><dd><code>ip :=: jp </code></dd> <dd><code>ip :=: NIL </code></dd></dl> while legal, will probably not do what might be expected. They will always return <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">FALSE, because they are comparing the actual addresses of the variables <code>ip</code> and <code>jp</code>, rather than what they point to. To achieve the right effect, one would have to write <dl><dd><code>ip :=: REF INT(jp) </code></dd> <dd><code>ip :=: REF INT(NIL) </code></dd></dl> <div class="mw-heading mw-heading4"><h4 id="Special_characters">Special characters</h4>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=28" title="Edit section: Special characters">edit</a>]</div> <dl><dd><figure typeof="mw:File/Thumb"><a href="/wiki/File:APL-keybd2.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/9/9f/APL-keybd2.svg/600px-APL-keybd2.svg.png" decoding="async" width="600" height="183" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/9/9f/APL-keybd2.svg/900px-APL-keybd2.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/9/9f/APL-keybd2.svg/1200px-APL-keybd2.svg.png 2x" data-file-width="410" data-file-height="125" /></a><figcaption><a href="/wiki/IBM_2741" title="IBM 2741">IBM 2741</a> keyboard with APL symbols</figcaption></figure></dd></dl> Most of Algol's "special" characters (⊂, ≡, ␣, ×, ÷, ≤, ≥, ≠, ¬, ⊃, ≡, ∨, ∧, →, ↓, ↑, ⌊, ⌈, ⎩, ⎧, ⊥, ⏨, ¢, ○ and □) can be found on the <a href="/wiki/IBM_2741" title="IBM 2741">IBM 2741</a> keyboard with the <a href="/wiki/APL_(programming_language)#Hardware" title="APL (programming language)">APL</a> "golf-ball" print head inserted; these became available in the mid-1960s while ALGOL 68 was being drafted. These characters are also part of the <a href="/wiki/Unicode" title="Unicode">Unicode</a> standard and most of them are available in several popular <a href="/wiki/Font" title="Font">fonts</a>. <div class="mw-heading mw-heading3"><h3 id="transput:_Input_and_output">transput: Input and output</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=29" title="Edit section: transput: Input and output">edit</a>]</div> Transput is the term used to refer to ALGOL 68's input and output facilities. It includes pre-defined procedures for unformatted, formatted and binary transput. Files and other transput devices are handled in a consistent and machine-independent manner. The following example prints out some unformatted output to the standard output device: <pre> print ((newpage, "Title", newline, "Value of i is ", i, "and x[i] is ", x[i], newline)) </pre> Note the predefined procedures <code>newpage</code> and <code>newline</code> passed as arguments. <div class="mw-heading mw-heading4"><h4 id="Books,_channels_and_files">Books, channels and files</h4>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=30" title="Edit section: Books, channels and files">edit</a>]</div> The TRANSPUT is considered to be of BOOKS, CHANNELS and FILES: <ul><li>Books are made up of pages, lines and characters, and may be backed up by files. <ul><li>A specific book can be located by name with a call to <code>match</code>.</li></ul></li> <li>CHANNELs correspond to physical devices. e.g. card punches and printers. <ul><li>Three standard channels are distinguished: stand in channel, stand out channel, stand back channel.</li></ul></li> <li>A FILE is a means of communicating between a program and a book that has been opened via some channel. <ul><li>The MOOD of a file may be read, write, char, bin, and opened.</li> <li>transput procedures include: <code>establish, create, open, associate, lock, close, scratch</code>.</li> <li>position enquires: <code>char number, line number, page number</code>.</li> <li>layout routines include: <ul><li><code>space</code>, <code>backspace</code>, <code>newline</code>, <code>newpage</code>.</li> <li><code>get good line, get good page, get good book</code>, and <code>PROC set=(REF FILE f, INT page,line,char)VOID:</code></li></ul></li> <li>A file has event routines. e.g. <code>on logical file end, on physical file end, on page end, on line end, on format end, on value error, on char error</code>.</li></ul></li></ul> <div class="mw-heading mw-heading4"><h4 id="formatted_transput">formatted transput</h4>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=31" title="Edit section: formatted transput">edit</a>]</div> "Formatted transput" in ALGOL 68's transput has its own syntax and patterns (functions), with FORMATs embedded between two $ characters.<a href="#cite_note-50">[50]</a> Examples: <pre> printf (($2l"The sum is:"x, g(0)$, m + n)); ¢ prints the same as: ¢ print ((new line, new line, "The sum is:", space, whole (m + n, 0)) </pre> <div class="mw-heading mw-heading3"><h3 id="par:_Parallel_processing">par: Parallel processing</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=32" title="Edit section: par: Parallel processing">edit</a>]</div> ALGOL 68 supports programming of parallel processing. Using the keyword PAR, a collateral clause is converted to a parallel clause, where the synchronisation of actions is controlled using <a href="/wiki/Semaphore_(programming)" title="Semaphore (programming)">semaphores</a>. In A68G the parallel actions are mapped to threads when available on the hosting <a href="/wiki/Operating_system" title="Operating system">operating system</a>. In A68S a different paradigm of parallel processing was implemented (see below). <pre>PROC eat = VOID: ( muffins-:=1; print(("Yum!",new line))), speak = VOID: ( words-:=1; print(("Yak...",new line)));   INT muffins := 4, words := 8; SEMA mouth = LEVEL 1;   PAR BEGIN WHILE muffins > 0 DO DOWN mouth; eat; UP mouth OD, WHILE words > 0 DO DOWN mouth; speak; UP mouth OD END </pre> <div class="mw-heading mw-heading3"><h3 id="Miscellaneous">Miscellaneous</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=33" title="Edit section: Miscellaneous">edit</a>]</div> For its technical intricacies, ALGOL 68 needs a cornucopia of methods to deny the existence of something: <pre>SKIP, "~" or "?"C – an undefined value always syntactically valid, EMPTY – the only value admissible to VOID, needed for selecting VOID in a UNION, VOID – syntactically like a MODE, but not one, NIL or "○" – a name not denoting anything, of an unspecified reference mode, () or specifically [1:0]INT – a vacuum is an empty array (here specifically of MODE []INT). undefined – a standards reports procedure raising an exception in the runtime system. ℵ – Used in the standards report to inhibit <a href="/wiki/Type_introspection" title="Type introspection">introspection</a> of certain types. e.g. SEMA </pre> The term NIL IS var always evaluates to TRUE for any variable (but see above for correct use of IS :/=:), whereas it is not known to which value a comparison x < SKIP evaluates for any integer x. ALGOL 68 leaves intentionally undefined what happens in case of <a href="/wiki/Integer_overflow" title="Integer overflow">integer overflow</a>, the integer bit representation, and the degree of numerical accuracy for floating point. Both official reports included some advanced features that were not part of the standard language. These were indicated with an ℵ and considered effectively private. Examples include "≮" and "≯" for templates, the OUTTYPE/INTYPE for crude <a href="/wiki/Duck_typing" title="Duck typing">duck typing</a>, and the STRAIGHTOUT and STRAIGHTIN operators for "straightening" nested arrays and structures <div class="mw-heading mw-heading2"><h2 id="Examples_of_use">Examples of use</h2>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=34" title="Edit section: Examples of use">edit</a>]</div> <div class="mw-heading mw-heading3"><h3 id="Code_sample">Code sample</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=35" title="Edit section: Code sample">edit</a>]</div> This sample program implements the <a href="/wiki/Sieve_of_Eratosthenes" title="Sieve of Eratosthenes">Sieve of Eratosthenes</a> to find all the <a href="/wiki/Prime_number" title="Prime number">prime numbers</a> that are less than 100. NIL is the ALGOL 68 analogue of the null pointer in other languages. The notation x OF y accesses a member x of a STRUCT y. <pre>BEGIN # Algol-68 prime number sieve, functional style #   PROC error = (STRING s) VOID: (print(( newline, " error: ", s, newline)); GOTO stop); PROC one to = (INT n) LIST: (PROC f = (INT m,n) LIST: (m>n | NIL | cons(m, f(m+1,n))); f(1,n));   MODE LIST = REF NODE; MODE NODE = STRUCT (INT h, LIST t); PROC cons = (INT n, LIST l) LIST: HEAP NODE := (n,l); PROC hd = (LIST l) INT: ( l IS NIL | error("hd NIL"); SKIP | h OF l ); PROC tl = (LIST l) LIST: ( l IS NIL | error("tl NIL"); SKIP | t OF l ); PROC show = (LIST l) VOID: ( l ISNT NIL | print((" ",whole(hd(l),0))); show(tl(l)));   PROC filter = (PROC (INT) BOOL p, LIST l) LIST: IF l IS NIL THEN NIL ELIF p(hd(l)) THEN cons(hd(l), filter(p,tl(l))) ELSE filter(p, tl(l)) FI;   PROC sieve = (LIST l) LIST: IF l IS NIL THEN NIL ELSE PROC not multiple = (INT n) BOOL: n MOD hd(l) ~= 0; cons(hd(l), sieve( filter( not multiple, tl(l) ))) FI;   PROC primes = (INT n) LIST: sieve( tl( one to(n) ));   show( primes(100) ) END </pre> <div class="mw-heading mw-heading3"><h3 id="Operating_systems_written_in_ALGOL_68">Operating systems written in ALGOL 68</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=36" title="Edit section: Operating systems written in ALGOL 68">edit</a>]</div> <ul><li><a href="/wiki/Cambridge_CAP_computer" class="mw-redirect" title="Cambridge CAP computer">Cambridge CAP computer</a> – All procedures constituting the operating system were written in <a href="/wiki/ALGOL_68C" title="ALGOL 68C">ALGOL 68C</a>, although several other closely associated protected procedures, such as a paginator, are written in <a href="/wiki/BCPL" title="BCPL">BCPL</a>.<a href="#cite_note-51">[51]</a></li> <li>Eldon 3 – Developed at <a href="/wiki/Leeds_University" class="mw-redirect" title="Leeds University">Leeds University</a> for the <a href="/wiki/ICT_1900_series" title="ICT 1900 series">ICL 1900</a> was written in <a href="/wiki/ALGOL_68-R" title="ALGOL 68-R">ALGOL 68-R</a>.<a href="#cite_note-eldon-52">[52]</a></li> <li><a href="/wiki/Flex_machine" title="Flex machine">Flex machine</a> – The hardware was custom and microprogrammable, with an operating system, (modular) compiler, editor, garbage collector and filing system all written in <a href="/wiki/ALGOL_68RS" title="ALGOL 68RS">ALGOL 68RS</a>. The command shell Curt<a href="#cite_note-53">[53]</a> was designed to access typed data similar to Algol-68 modes.</li> <li><a href="/wiki/ICL_VME" title="ICL VME">VME</a> – <a href="/wiki/S3_(programming_language)" title="S3 (programming language)">S3</a> was the implementation language of the <a href="/wiki/Operating_system" title="Operating system">operating system</a> VME. S3 was based on ALGOL 68 but with data types and operators aligned to those offered by the <a href="/wiki/ICL_2900_Series" title="ICL 2900 Series">ICL 2900 Series</a>.</li></ul> Note: The Soviet Era computers <a href="/wiki/Elbrus_(computer)" title="Elbrus (computer)">Эльбрус-1 (Elbrus-1)</a> and Эльбрус-2 were created using high-level language Эль-76 (AL-76), rather than the traditional assembly. Эль-76 resembles Algol-68, The main difference is the dynamic binding types in Эль-76 supported at the hardware level. Эль-76 is used for application, job control, system programming.<a href="#cite_note-54">[54]</a> <div class="mw-heading mw-heading3"><h3 id="Applications">Applications</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=37" title="Edit section: Applications">edit</a>]</div> Both <a href="/wiki/ALGOL_68C" title="ALGOL 68C">ALGOL 68C</a> and <a href="/wiki/ALGOL_68-R" title="ALGOL 68-R">ALGOL 68-R</a> are written in ALGOL 68, effectively making ALGOL 68 an application of itself. Other applications include: <ul><li><a href="/wiki/ELLA_(programming_language)" title="ELLA (programming language)">ELLA</a> – a hardware description language and support toolset. Developed by the <a href="/wiki/Royal_Signals_and_Radar_Establishment" title="Royal Signals and Radar Establishment">Royal Signals and Radar Establishment</a> during the 1980s and 1990s.</li> <li><a href="/wiki/RAF_Strike_Command" title="RAF Strike Command">RAF Strike Command</a> System – "... 400K of error-free <a href="/wiki/ALGOL_68-RT" class="mw-redirect" title="ALGOL 68-RT">ALGOL 68-RT</a> code was produced with three man-years of work. ..."<a href="#cite_note-55">[55]</a></li></ul> <div class="mw-heading mw-heading3"><h3 id="Libraries_and_APIs">Libraries and APIs</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=38" title="Edit section: Libraries and APIs">edit</a>]</div> <ul><li><a href="/wiki/NAG_Numerical_Libraries" class="mw-redirect" title="NAG Numerical Libraries">NAG Numerical Libraries</a> – a <a href="/wiki/Software_library" class="mw-redirect" title="Software library">software library</a> of <a href="/wiki/Numerical_analysis" title="Numerical analysis">numerical analysis</a> routines. Supplied in ALGOL 68 during the 1980s.</li> <li>TORRIX – a programming system for operations on vectors and matrices over arbitrary fields and of variable size by S. G. van der Meulen and M. Veldhorst.<a href="#cite_note-torrix-56">[56]</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="Program_representation">Program representation</h2>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=39" title="Edit section: Program representation">edit</a>]</div> A feature of ALGOL 68, inherited from the <a href="/wiki/ALGOL" title="ALGOL">ALGOL</a> tradition, is its different representations. There is a representation language used to describe algorithms in printed work, a strict language (rigorously defined in the Report), and an official reference language intended to be used in compiler input. The examples contain BOLD typeface words, this is the STRICT language. ALGOL 68's reserved words are effectively in a different <a href="/wiki/Namespace" title="Namespace">namespace</a> from identifiers, and spaces are allowed in identifiers, so this next fragment is legal: <pre> INT a real int = 3 ; </pre> The programmer who writes executable code does not always have an option of BOLD typeface or underlining in the code as this may depend on hardware and cultural issues. Different methods to denote these identifiers have been devised. This is called a <a href="/wiki/Stropping_(programming)" class="mw-redirect" title="Stropping (programming)">stropping</a> regime. For example, all or some of the following may be available programming representations: <pre> INT a real int = 3; # the STRICT language # 'INT'A REAL INT = 3; # QUOTE stropping style # .INT A REAL INT = 3; # POINT stropping style # INT a real int = 3; # UPPER stropping style # int a_real_int = 3; # RES stropping style, there are 61 accepted reserved words # </pre> All implementations must recognize at least POINT, UPPER and RES inside PRAGMAT sections. Of these, POINT and UPPER stropping are quite common, while RES stropping is a contradiction to the specification (as there are no reserved words). QUOTE (single apostrophe quoting) was the original recommendation, while matched apostrophe quoting, common in ALGOL 60, is not used much in ALGOL 68.<a href="#cite_note-57">[57]</a> The following characters were recommended for portability, and termed "worthy characters" in the <a rel="nofollow" class="external text" href="http://www.fh-jena.de/~kleine/history/languages/Algol68-RR-HardwareRepresentation.pdf">Report on the Standard Hardware Representation of Algol 68</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140102201013/http://www.fh-jena.de/~kleine/history/languages/Algol68-RR-HardwareRepresentation.pdf">Archived</a> 2014-01-02 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>: <ul><li><style data-mw-deduplicate="TemplateStyles:r1041539562">.mw-parser-output .citation{word-wrap:break-word}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}</style><a href="#ref_worthy">^</a> Worthy Characters: ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 "#$%'()*+,-./:;<=>@[ ]_|</li></ul> This reflected a problem in the 1960s where some hardware didn't support lower-case, nor some other non-<a href="/wiki/ASCII" title="ASCII">ASCII</a> characters, indeed in the 1973 report it was written: "Four worthy characters — "|", "_", "[", and "]" — are often coded differently, even at installations which nominally use the same character set." <ul><li>Base characters: "Worthy characters" are a subset of "base characters".</li></ul> <div class="mw-heading mw-heading3"><h3 id="Example_of_different_program_representations">Example of different program representations</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=40" title="Edit section: Example of different program representations">edit</a>]</div> <table class="wikitable plainrowheaders"> <tbody><tr> <th scope="col">Representation </th> <th scope="col">Code </th></tr> <tr> <th scope="row">Algol68 "strict" as typically published </th> <td><style data-mw-deduplicate="TemplateStyles:r1195917819">.mw-parser-output .pre-borderless{border:none}</style><pre class="pre">¢ underline or bold typeface ¢ MODE XINT = INT; XINT sum sq:=0; FOR i WHILE sum sq≠70×70 DO sum sq+:=i↑2 OD</pre> </td></tr> <tr> <th scope="row">Quote stropping (like <a href="/wiki/Lightweight_markup_language#Text/font-face_formatting" title="Lightweight markup language">wikitext</a>) </th> <td><div class="mw-highlight mw-highlight-lang-text mw-content-ltr" dir="ltr"><pre>'pr' quote 'pr' 'mode' 'xint' = 'int'; 'xint' sum sq:=0; 'for' i 'while' sum sq≠70×70 'do' sum sq+:=i↑2 'od' </pre></div> </td></tr> <tr> <th scope="row">For a <a href="/wiki/List_of_binary_codes#Seven-bit_binary_codes" title="List of binary codes">7-bit</a> character code compiler </th> <td><div class="mw-highlight mw-highlight-lang-man mw-content-ltr" dir="ltr"><pre>.PR UPPER .PR MODE XINT = INT; XINT sum sq:=0; FOR i WHILE sum sq/=70*70 DO sum sq+:=i**2 OD </pre></div> </td></tr> <tr> <th scope="row">For a <a href="/wiki/Six-bit_character_code" title="Six-bit character code">6-bit</a> character code compiler </th> <td><div class="mw-highlight mw-highlight-lang-man mw-content-ltr" dir="ltr"><pre>.PR POINT .PR .MODE .XINT = .INT; .XINT SUM SQ:=0; .FOR I .WHILE SUM SQ .NE 70*70 .DO SUM SQ .PLUSAB I .UP 2 .OD </pre></div> </td></tr> <tr> <th scope="row">Algol68 using RES stropping (reserved word) </th> <td><div class="mw-highlight mw-highlight-lang-man mw-content-ltr" dir="ltr"><pre>.PR RES .PR mode .xint = int; .xint sum sq:=0; for i while sum sq≠70×70 do sum sq+:=i↑2 od </pre></div> </td></tr></tbody></table> ALGOL 68 allows for every natural language to define its own set of keywords Algol-68. As a result, programmers are able to write programs using keywords from their native language. Below is an example of a simple procedure that calculates "the day following", the code is in two languages: English and German.[<a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a>] <pre> # Next day date - English variant # MODE DATE = STRUCT(INT day, STRING month, INT year); PROC the day following = (DATE x) DATE: IF day OF x < length of month (month OF x, year OF x) THEN (day OF x + 1, month OF x, year OF x) ELIF month OF x = "December" THEN (1, "January", year OF x + 1) ELSE (1, successor of month (month OF x), year OF x) FI; </pre> <pre> # Nachfolgetag - Deutsche Variante # MENGE DATUM = TUPEL(GANZ tag, WORT monat, GANZ jahr); FUNKTION naechster tag nach = (DATUM x) DATUM: WENN tag VON x < monatslaenge(monat VON x, jahr VON x) DANN (tag VON x + 1, monat VON x, jahr VON x) WENNABER monat VON x = "Dezember" DANN (1, "Januar", jahr VON x + 1) ANSONSTEN (1, nachfolgemonat(monat VON x), jahr VON x) ENDEWENN; </pre> Russian/Soviet example: In English Algol68's case statement reads CASE ~ IN ~ OUT ~ ESAC, in <a href="/wiki/Cyrillic" class="mw-redirect" title="Cyrillic">Cyrillic</a> this reads выб ~ в ~ либо ~ быв. <div class="mw-heading mw-heading2"><h2 id="Revisions">Revisions</h2>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=41" title="Edit section: Revisions">edit</a>]</div> Except where noted (with a superscript), the language described above is that of the "Revised Report(r1)". <div class="mw-heading mw-heading3"><h3 id="The_language_of_the_unrevised_report">The language of the unrevised report</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=42" title="Edit section: The language of the unrevised report">edit</a>]</div> The original language (As per the "Final Report"<a href="#The_language_of_the_unrevised_report">r0</a>) differs in syntax of the mode cast, and it had the feature of proceduring, i.e. coercing the value of a term into a procedure which evaluates the term. Proceduring would be intended to make evaluations lazy. The most useful application could have been the short-circuited evaluation of Boolean operators. In: <pre>OP ANDF = (BOOL a,PROC BOOL b)BOOL:(a | b | FALSE); OP ORF = (BOOL a,PROC BOOL b)BOOL:(a | TRUE | b); </pre> b is only evaluated if a is true. As defined in ALGOL 68, it did not work as expected, for example in the code: <pre>IF FALSE ANDF CO proc bool: CO ( print ("Should not be executed"); TRUE) THEN ... </pre> against the programmers naïve expectations the print would be executed as it is only the value of the elaborated enclosed-clause after ANDF that was procedured. Textual insertion of the commented-out PROC BOOL: makes it work. Some implementations emulate the expected behaviour for this special case by extension of the language. Before revision, the programmer could decide to have the arguments of a procedure evaluated serially instead of collaterally by using semicolons instead of commas (<a rel="nofollow" class="external text" href="https://groups.google.com/group/comp.lang.misc/msg/03af5063e1662d4d">gomma</a>s). For example in: <pre>PROC test = (REAL a; REAL b) :... ... test (x PLUS 1, x); </pre> The first argument to test is guaranteed to be evaluated before the second, but in the usual: <pre>PROC test = (REAL a, b) :... ... test (x PLUS 1, x); </pre> then the compiler could evaluate the arguments in whatever order it felt like. <div class="mw-heading mw-heading3"><h3 id="Extension_proposals_from_IFIP_WG_2.1">Extension proposals from IFIP WG 2.1</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=43" title="Edit section: Extension proposals from IFIP WG 2.1">edit</a>]</div> After the revision of the report, some extensions to the language have been proposed to widen the applicability: <ul><li>partial parametrisation (aka <a href="/wiki/Currying#Motivation" title="Currying">Currying</a>): creation of functions (with fewer parameters) by specification of some, but not all parameters for a call, e.g. a function logarithm of two parameters, base and argument, could be specialised to natural, binary or decadic log,<a href="#cite_note-58">[58]</a></li> <li>module extension: for support of external linkage, two mechanisms were proposed, bottom-up definition modules, a more powerful version of the facilities from <a href="/wiki/ALGOL_68-R" title="ALGOL 68-R">ALGOL 68-R</a> and top-down holes, similar to the <code>ENVIRON</code> and <code>USING</code> clauses from <a href="/wiki/ALGOL_68C" title="ALGOL 68C">ALGOL 68C</a><a href="#cite_note-modules-59">[59]</a></li> <li>mode parameters: for implementation of limited parametrical polymorphism (most operations on data structures like lists, trees or other data containers can be specified without touching the pay load).<a href="#cite_note-60">[60]</a></li></ul> So far, only partial parametrisation has been implemented, in Algol 68 Genie. <div class="mw-heading mw-heading3"><h3 id="True_ALGOL_68s_specification_and_implementation_timeline">True ALGOL 68s specification and implementation timeline</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=44" title="Edit section: True ALGOL 68s specification and implementation timeline">edit</a>]</div> <table class="wikitable sortable"> <tbody><tr style="background:#ccc;"> <th>Name</th> <th>Year</th> <th>Purpose</th> <th>State</th> <th>Description</th> <th>Target CPU</th> <th>Licensing</th> <th>Implementation language </th></tr> <tr> <td><a href="/w/index.php?title=Generalized_ALGOL&action=edit&redlink=1" class="new" title="Generalized ALGOL (page does not exist)">Generalized ALGOL</a></td> <td>1962</td> <td>Scientific</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/23px-Flag_of_the_Netherlands.svg.png" decoding="async" width="23" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/35px-Flag_of_the_Netherlands.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/45px-Flag_of_the_Netherlands.svg.png 2x" data-file-width="900" data-file-height="600" /> <a href="/wiki/Netherlands" title="Netherlands">NLD</a></td> <td>ALGOL for generalised grammars</td> <td></td> <td></td> <td> </td></tr> <tr> <td><a href="/wiki/ALGOL_Y" title="ALGOL Y">ALGOL Y</a>Y</td> <td>1966</td> <td>Draft proposal</td> <td>Intl</td> <td>First version of Algol 68</td> <td>Specification</td> <td><a href="/wiki/Association_for_Computing_Machinery" title="Association for Computing Machinery">ACM</a></td> <td> </td></tr> <tr> <td>ALGOL 68DR</td> <td>1968</td> <td>Draft proposal</td> <td>Intl</td> <td>IFIP WG 2.1 Draft Report</td> <td>Specification – March</td> <td>ACM</td> <td> </td></tr> <tr> <td>ALGOL 68<a href="#The_language_of_the_unrevised_report">r0</a></td> <td>1968</td> <td>Standard</td> <td>Intl</td> <td>IFIP WG 2.1 Final Report</td> <td>Specification – August</td> <td>ACM</td> <td> </td></tr> <tr> <td><a href="/wiki/ALGOL_68-R" title="ALGOL 68-R">ALGOL 68-R</a>R</td> <td>1970</td> <td>Military</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/23px-Flag_of_the_United_Kingdom.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/35px-Flag_of_the_United_Kingdom.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/46px-Flag_of_the_United_Kingdom.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a></td> <td></td> <td><a href="/wiki/ICT_1900_series" title="ICT 1900 series">ICL 1900</a></td> <td></td> <td>ALGOL 60 </td></tr> <tr> <td><a href="/w/index.php?title=EPOS_ALGOL&action=edit&redlink=1" class="new" title="EPOS ALGOL (page does not exist)">EPOS ALGOL</a>E</td> <td>1971</td> <td>Scientific</td> <td></td> <td></td> <td></td> <td></td> <td> </td></tr> <tr> <td><a href="/wiki/ALGOL_68RS" title="ALGOL 68RS">ALGOL 68RS</a>RS</td> <td>1972</td> <td>Military</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/23px-Flag_of_the_United_Kingdom.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/35px-Flag_of_the_United_Kingdom.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/46px-Flag_of_the_United_Kingdom.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a></td> <td>Portable compiler system</td> <td>ICL 2900/Series 39, Multics, VMS & C generator (1993)</td> <td><a href="/wiki/Crown_Copyright" class="mw-redirect" title="Crown Copyright">Crown Copyright</a></td> <td>ALGOL 68RS </td></tr> <tr> <td>Algol 68 with areas</td> <td>1972</td> <td>Experimental & other</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/23px-Flag_of_the_United_Kingdom.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/35px-Flag_of_the_United_Kingdom.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/46px-Flag_of_the_United_Kingdom.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a></td> <td>Addition of areas to Algol 68</td> <td></td> <td></td> <td> </td></tr> <tr> <td>Mini ALGOL 68</td> <td>1973</td> <td>Research</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/23px-Flag_of_the_Netherlands.svg.png" decoding="async" width="23" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/35px-Flag_of_the_Netherlands.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/45px-Flag_of_the_Netherlands.svg.png 2x" data-file-width="900" data-file-height="600" /> <a href="/wiki/Netherlands" title="Netherlands">NLD</a></td> <td><a rel="nofollow" class="external text" href="http://oai.cwi.nl/oai/asset/9494/9494A.pdf">"An interpreter for simple Algol 68 Programs"</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110718172314/http://oai.cwi.nl/oai/asset/9494/9494A.pdf">Archived</a> 2011-07-18 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></td> <td>Portable interpreter</td> <td><a href="/wiki/Mathematisch_Centrum" class="mw-redirect" title="Mathematisch Centrum">Mathematisch Centrum</a></td> <td><a href="/wiki/ALGOL_60" title="ALGOL 60">ALGOL 60</a> </td></tr> <tr> <td><a href="/w/index.php?title=OREGANO&action=edit&redlink=1" class="new" title="OREGANO (page does not exist)">OREGANO</a></td> <td>1973</td> <td>Research</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/a4/Flag_of_the_United_States.svg/23px-Flag_of_the_United_States.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/a4/Flag_of_the_United_States.svg/35px-Flag_of_the_United_States.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/a4/Flag_of_the_United_States.svg/46px-Flag_of_the_United_States.svg.png 2x" data-file-width="1235" data-file-height="650" /> <a href="/wiki/United_States" title="United States">US</a></td> <td>"The importance of implementation models."</td> <td></td> <td><a href="/wiki/UCLA" class="mw-redirect" title="UCLA">UCLA</a></td> <td> </td></tr> <tr> <td><a href="/wiki/ALGOL_68C" title="ALGOL 68C">ALGOL 68C</a>C</td> <td>1975</td> <td>Scientific</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/23px-Flag_of_the_United_Kingdom.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/35px-Flag_of_the_United_Kingdom.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/46px-Flag_of_the_United_Kingdom.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a></td> <td>Cambridge Algol 68</td> <td><a href="/wiki/International_Computers_Limited" title="International Computers Limited">ICL</a>, IBM 360, PDP 10 & Unix, <a href="/wiki/Telefunken" title="Telefunken">Telefunken</a>, Tesla & <a href="/wiki/Z80" class="mw-redirect" title="Z80">Z80</a> (1980)<a href="#cite_note-61">[61]</a></td> <td>Cambridge</td> <td>ALGOL 68C </td></tr> <tr> <td>ALGOL 68 Revised Report<a href="#Revisions">r1</a></td> <td>1975</td> <td>Standard</td> <td>Intl</td> <td>IFIP WG 2.1 Revised Report</td> <td>Specification</td> <td>ACM</td> <td> </td></tr> <tr> <td><a href="/w/index.php?title=Algol_H&action=edit&redlink=1" class="new" title="Algol H (page does not exist)">Algol H</a>H</td> <td>1975</td> <td>Experimental & other</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/23px-Flag_of_the_United_Kingdom.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/35px-Flag_of_the_United_Kingdom.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/46px-Flag_of_the_United_Kingdom.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a></td> <td>Proposed extensions to the mode system of Algol 68</td> <td>Specification</td> <td></td> <td><a href="/wiki/ALGOL_W" title="ALGOL W">ALGOL W</a> </td></tr> <tr> <td><a href="/wiki/Odra_(computer)" title="Odra (computer)">Odra</a> Algol 68</td> <td>1976</td> <td>practical uses</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Flag_of_the_Soviet_Union.svg/23px-Flag_of_the_Soviet_Union.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Flag_of_the_Soviet_Union.svg/35px-Flag_of_the_Soviet_Union.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Flag_of_the_Soviet_Union.svg/46px-Flag_of_the_Soviet_Union.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/Soviet_Union" title="Soviet Union">Soviet Union</a>/<img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/1/12/Flag_of_Poland.svg/23px-Flag_of_Poland.svg.png" decoding="async" width="23" height="14" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/1/12/Flag_of_Poland.svg/35px-Flag_of_Poland.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/1/12/Flag_of_Poland.svg/46px-Flag_of_Poland.svg.png 2x" data-file-width="1280" data-file-height="800" /> <a href="/wiki/Poland" title="Poland">Poland</a></td> <td></td> <td>Odra 1204/IL</td> <td><a href="/wiki/Copyright_law_of_the_Soviet_Union" title="Copyright law of the Soviet Union">Soviet</a></td> <td><a href="/wiki/ALGOL_60" title="ALGOL 60">ALGOL 60</a> </td></tr> <tr> <td>Oklahoma ALGOL 68</td> <td>1976</td> <td>programming instruction</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/a4/Flag_of_the_United_States.svg/23px-Flag_of_the_United_States.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/a4/Flag_of_the_United_States.svg/35px-Flag_of_the_United_States.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/a4/Flag_of_the_United_States.svg/46px-Flag_of_the_United_States.svg.png 2x" data-file-width="1235" data-file-height="650" /> <a href="/wiki/United_States" title="United States">USA</a></td> <td><a href="/wiki/Oklahoma_State_University" title="Oklahoma State University">Oklahoma State University</a> implementation<a href="#cite_note-62">[62]</a></td> <td><a href="/wiki/IBM_1130" title="IBM 1130">IBM 1130</a> and <a href="/wiki/System/370" class="mw-redirect" title="System/370">System/370</a>/158</td> <td style="background: var(--background-color-interactive, #EEE); color: var(--color-base, black); vertical-align: middle; white-space: nowrap; text-align: center;" class="table-Unknown">Unknown</td> <td>ANSI <a href="/wiki/Fortran_66" class="mw-redirect" title="Fortran 66">Fortran 66</a>. </td></tr> <tr> <td>Berlin ALGOL 68</td> <td>1977</td> <td>Research</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/b/ba/Flag_of_Germany.svg/23px-Flag_of_Germany.svg.png" decoding="async" width="23" height="14" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/b/ba/Flag_of_Germany.svg/35px-Flag_of_Germany.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/b/ba/Flag_of_Germany.svg/46px-Flag_of_Germany.svg.png 2x" data-file-width="1000" data-file-height="600" /> <a href="/wiki/Germany" title="Germany">DE</a></td> <td><a rel="nofollow" class="external text" href="http://doi.acm.org/10.1145/872738.807149">"The Berlin ALGOL 68 implementation"</a> &<a href="#cite_note-63">[63]</a></td> <td>An Abstract ALGOL 68 Machine – machine independent Compiler</td> <td><a href="/wiki/Technische_Universit%C3%A4t_Berlin" title="Technische Universität Berlin">Technische Universität Berlin</a></td> <td><a href="/wiki/Compiler_Description_Language" title="Compiler Description Language">CDL 2</a> </td></tr> <tr> <td><a href="/wiki/FLACC" title="FLACC">FLACC</a>F</td> <td>1977</td> <td>Multi-purpose</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Flag_of_Canada_%28Pantone%29.svg/23px-Flag_of_Canada_%28Pantone%29.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Flag_of_Canada_%28Pantone%29.svg/35px-Flag_of_Canada_%28Pantone%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d9/Flag_of_Canada_%28Pantone%29.svg/46px-Flag_of_Canada_%28Pantone%29.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/Canada" title="Canada">CAN</a></td> <td>Revised Report complete implementation with debug features</td> <td>System/370</td> <td>lease, Chion Corporation</td> <td>Assembler </td></tr> <tr> <td><a href="/wiki/ALGOL_68-RT" class="mw-redirect" title="ALGOL 68-RT">ALGOL 68-RT</a>RT</td> <td>1979</td> <td>Scientific</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/23px-Flag_of_the_United_Kingdom.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/35px-Flag_of_the_United_Kingdom.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/46px-Flag_of_the_United_Kingdom.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a></td> <td>Parallel ALGOL 68-R</td> <td></td> <td></td> <td> </td></tr> <tr> <td><a href="/w/index.php?title=RS_Algol&action=edit&redlink=1" class="new" title="RS Algol (page does not exist)">RS Algol</a>rs</td> <td>1979</td> <td>Scientific</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/23px-Flag_of_the_United_Kingdom.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/35px-Flag_of_the_United_Kingdom.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/46px-Flag_of_the_United_Kingdom.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a></td> <td></td> <td></td> <td></td> <td> </td></tr> <tr> <td>ALGOL 68+</td> <td>1980</td> <td>Scientific</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/23px-Flag_of_the_Netherlands.svg.png" decoding="async" width="23" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/35px-Flag_of_the_Netherlands.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/45px-Flag_of_the_Netherlands.svg.png 2x" data-file-width="900" data-file-height="600" /> <a href="/wiki/Netherlands" title="Netherlands">NLD</a></td> <td>Proposed superlanguage of ALGOL 68<a href="#cite_note-64">[64]</a></td> <td></td> <td></td> <td> </td></tr> <tr> <td><a href="/wiki/M-220" class="mw-redirect" title="M-220">M-220</a> ALGOL 68</td> <td></td> <td></td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Flag_of_the_Soviet_Union.svg/23px-Flag_of_the_Soviet_Union.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Flag_of_the_Soviet_Union.svg/35px-Flag_of_the_Soviet_Union.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Flag_of_the_Soviet_Union.svg/46px-Flag_of_the_Soviet_Union.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/Soviet_Union" title="Soviet Union">Soviet Union</a></td> <td></td> <td>M-220</td> <td><a href="/wiki/Copyright_law_of_the_Soviet_Union" title="Copyright law of the Soviet Union">Soviet</a></td> <td><a href="/wiki/EPSILON_(programming_language)" title="EPSILON (programming language)">EPSILON</a> </td></tr> <tr> <td><a href="/w/index.php?title=Leningrad_ALGOL_68&action=edit&redlink=1" class="new" title="Leningrad ALGOL 68 (page does not exist)">Leningrad ALGOL 68</a>L</td> <td>1980</td> <td>Telecommunications</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Flag_of_the_Soviet_Union.svg/23px-Flag_of_the_Soviet_Union.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Flag_of_the_Soviet_Union.svg/35px-Flag_of_the_Soviet_Union.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Flag_of_the_Soviet_Union.svg/46px-Flag_of_the_Soviet_Union.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/Soviet_Union" title="Soviet Union">Soviet Union</a></td> <td>Full language + modules</td> <td>IBM, DEC, CAMCOH, PS 1001 & PC</td> <td><a href="/wiki/Copyright_law_of_the_Soviet_Union" title="Copyright law of the Soviet Union">Soviet</a></td> <td> </td></tr> <tr> <td><a href="/wiki/Interactive_ALGOL_68" title="Interactive ALGOL 68">Interactive ALGOL 68</a>I</td> <td>1983</td> <td></td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/23px-Flag_of_the_United_Kingdom.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/35px-Flag_of_the_United_Kingdom.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/46px-Flag_of_the_United_Kingdom.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a></td> <td><a href="/wiki/Incremental_compilation" class="mw-redirect" title="Incremental compilation">Incremental compilation</a></td> <td>PC</td> <td>Noncommercial <a href="/wiki/Shareware" title="Shareware">shareware</a></td> <td> </td></tr> <tr> <td><a href="/wiki/ALGOL_68S" title="ALGOL 68S">ALGOL 68S</a>S</td> <td>1985</td> <td>Scientific</td> <td>Intl</td> <td>Sun version of ALGOL 68</td> <td><a href="/wiki/Sun-3" title="Sun-3">Sun-3</a>, Sun <a href="/wiki/SPARC" title="SPARC">SPARC</a> (under <a href="/wiki/SunOS" title="SunOS">SunOS</a> 4.1 & <a href="/wiki/Solaris_(operating_system)" class="mw-redirect" title="Solaris (operating system)">Solaris</a> 2), <a href="/wiki/Atari" title="Atari">Atari</a> ST (under <a href="/wiki/Atari_ST" title="Atari ST">GEMDOS</a>), <a href="/wiki/Acorn_Archimedes" title="Acorn Archimedes">Acorn Archimedes</a> (under <a href="/wiki/RISC_OS" title="RISC OS">RISC OS</a>), <a href="/wiki/VAX-11" title="VAX-11">VAX-11</a> under <a href="/wiki/Ultrix-32" class="mw-redirect" title="Ultrix-32">Ultrix-32</a></td> <td></td> <td> </td></tr> <tr> <td>Algol68toC<a href="#cite_note-65">[65]</a> (ctrans)</td> <td>1985</td> <td>Electronics</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/23px-Flag_of_the_United_Kingdom.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/35px-Flag_of_the_United_Kingdom.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/46px-Flag_of_the_United_Kingdom.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a></td> <td>ctrans from <a href="/wiki/ELLA_(programming_language)" title="ELLA (programming language)">ELLA</a> <a href="/wiki/ALGOL_68RS" title="ALGOL 68RS">ALGOL 68RS</a></td> <td>Portable C generator  </td> <td style="background: #9EFF9E; color:black; vertical-align: middle; text-align: center;" class="active table-active"><a href="/wiki/Open-source_software" title="Open-source software">Open-source software</a> 1995</td> <td>ALGOL 68RS </td></tr> <tr> <td>MK2 <a href="/wiki/Interactive_ALGOL_68" title="Interactive ALGOL 68">Interactive ALGOL 68</a></td> <td>1992</td> <td></td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/23px-Flag_of_the_United_Kingdom.svg.png" decoding="async" width="23" height="12" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/35px-Flag_of_the_United_Kingdom.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/a/ae/Flag_of_the_United_Kingdom.svg/46px-Flag_of_the_United_Kingdom.svg.png 2x" data-file-width="1200" data-file-height="600" /> <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a></td> <td><a href="/wiki/Incremental_compilation" class="mw-redirect" title="Incremental compilation">Incremental compilation</a></td> <td>PC</td> <td>Noncommercial shareware<a href="#cite_note-66">[66]</a></td> <td> </td></tr> <tr> <td>Algol 68 GenieG</td> <td>2001</td> <td>Full language</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/23px-Flag_of_the_Netherlands.svg.png" decoding="async" width="23" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/35px-Flag_of_the_Netherlands.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/45px-Flag_of_the_Netherlands.svg.png 2x" data-file-width="900" data-file-height="600" /> <a href="/wiki/Netherlands" title="Netherlands">NLD</a></td> <td>Includes standard collateral clause</td> <td>Portable interpreter </td> <td style="background: #DFF; color:black; vertical-align: middle; text-align: center;" class="free table-free"><a href="/wiki/GNU_General_Public_License" title="GNU General Public License">GNU GPL</a> </td> <td><a href="/wiki/C_(programming_language)" title="C (programming language)">C</a> </td></tr> <tr> <td>Algol 68 Genie version 2.0.0</td> <td>2010</td> <td>Full language</td> <td><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/23px-Flag_of_the_Netherlands.svg.png" decoding="async" width="23" height="15" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/35px-Flag_of_the_Netherlands.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/20/Flag_of_the_Netherlands.svg/45px-Flag_of_the_Netherlands.svg.png 2x" data-file-width="900" data-file-height="600" /> <a href="/wiki/Netherlands" title="Netherlands">NLD</a></td> <td></td> <td>Portable interpreter; optional compilation of selected units </td> <td style="background: #DFF; color:black; vertical-align: middle; text-align: center;" class="free table-free"><a href="/wiki/GNU_General_Public_License" title="GNU General Public License">GNU GPL</a> </td> <td><a href="/wiki/C_(programming_language)" title="C (programming language)">C</a> </td></tr></tbody></table> The <a href="/wiki/S3_(programming_language)" title="S3 (programming language)">S3 language</a> that was used to write the <a href="/wiki/ICL_VME" title="ICL VME">ICL VME</a> operating system and much other system software on the <a href="/wiki/ICL_2900_Series" title="ICL 2900 Series">ICL 2900 Series</a> was a direct derivative of Algol 68. However, it omitted many of the more complex features, and replaced the basic modes with a set of data types that mapped directly to the 2900 Series hardware architecture. <div class="mw-heading mw-heading3"><h3 id="Implementation_specific_extensions">Implementation specific extensions</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=45" title="Edit section: Implementation specific extensions">edit</a>]</div> ALGOL 68R from <a href="/wiki/Royal_Radar_Establishment" title="Royal Radar Establishment">RRE</a> was the first ALGOL 68 subset implementation, running on the <a href="/wiki/ICT_1900_series" title="ICT 1900 series">ICL 1900</a>. Based on the original language, the main subset restrictions were definition before use and no parallel processing. This compiler was popular in <a href="/wiki/United_Kingdom" title="United Kingdom">UK</a> universities in the 1970s, where many <a href="/wiki/Computer_science" title="Computer science">computer science</a> students learnt ALGOL 68 as their first programming language; the compiler was renowned for good error messages. ALGOL 68RS(RS) from <a href="/wiki/Royal_Signals_and_Radar_Establishment" title="Royal Signals and Radar Establishment">RSRE</a> was a portable compiler system written in ALGOL 68RS (bootstrapped from ALGOL 68R), and implemented on a variety of systems including the <a href="/wiki/ICL_2900_Series" title="ICL 2900 Series">ICL 2900</a>/<a href="/wiki/ICL_Series_39" title="ICL Series 39">Series 39</a>, <a href="/wiki/Multics" title="Multics">Multics</a> and <a href="/wiki/VAX" title="VAX">DEC VAX/VMS</a>. The language was based on the Revised Report, but with similar subset restrictions to ALGOL 68R. This compiler survives in the form of an Algol68-to-C compiler. In ALGOL 68S(S) from <a href="/wiki/Carnegie_Mellon_University" title="Carnegie Mellon University">Carnegie Mellon University</a> the power of parallel processing was improved by adding an orthogonal extension, eventing. Any variable declaration containing keyword EVENT made assignments to this variable eligible for parallel evaluation, i.e. the right hand side was made into a procedure which was moved to one of the processors of the <a href="/wiki/C.mmp" title="C.mmp">C.mmp</a> multiprocessor system. Accesses to such variables were delayed after termination of the assignment. <a href="/wiki/University_of_Cambridge" title="University of Cambridge">Cambridge</a> <a href="/wiki/ALGOL_68C" title="ALGOL 68C">ALGOL 68C</a>(C) was a portable compiler that implemented a subset of ALGOL 68, restricting operator definitions and omitting garbage collection, flexible rows and formatted transput. Algol 68 Genie(G) by M. van der Veer is an ALGOL 68 implementation for today's computers and operating systems. "Despite good intentions, a programmer may violate portability by inadvertently employing a local extension. To guard against this, each implementation should provide a PORTCHECK pragmat option. While this option is in force, the compiler prints a message for each construct that it recognizes as violating some portability constraint."<a href="#cite_note-67">[67]</a> <div class="mw-heading mw-heading2"><h2 id="Quotes">Quotes</h2>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=46" title="Edit section: Quotes">edit</a>]</div> <ul><li>... The scheme of type composition adopted by C owes considerable debt to Algol 68, although it did not, perhaps, emerge in a form that Algol's adherents would approve of. The central notion I captured from Algol was a type structure based on atomic types (including structures), composed into arrays, pointers (references), and functions (procedures). Algol 68's concept of unions and casts also had an influence that appeared later. <a href="/wiki/Dennis_Ritchie" title="Dennis Ritchie">Dennis Ritchie</a> Apr 1993.<a href="#cite_note-a68-c1-2">[2]</a></li> <li>... C does not descend from Algol 68 is true, yet there was influence, much of it so subtle that it is hard to recover even when I think hard. In particular, the union type (a late addition to C) does owe to A68, not in any details, but in the idea of having such a type at all. More deeply, the type structure in general and even, in some strange way, the declaration syntax (the type-constructor part) was inspired by A68. And yes, of course, "long". <a href="/wiki/Dennis_Ritchie" title="Dennis Ritchie">Dennis Ritchie</a>, 18 June 1988<a href="#cite_note-a68-c2-4">[4]</a></li> <li>"Congratulations, your Master has done it" – <a href="/wiki/Niklaus_Wirth" title="Niklaus Wirth">Niklaus Wirth</a><a href="#cite_note-68">[68]</a></li> <li>The more I see of it, the more unhappy I become – E. W. Dijkstra, 1968<a href="#cite_note-69">[69]</a></li> <li>[...] it was said that A68's popularity was inversely proportional to [...] the distance from Amsterdam – <a href="/wiki/Guido_van_Rossum" title="Guido van Rossum">Guido van Rossum</a><a href="#cite_note-70">[70]</a></li> <li>[...] The best we could do was to send with it a minority report, stating our considered view that, "... as a tool for the reliable creation of sophisticated programs, the language was a failure." [...] – <a href="/wiki/Tony_Hoare" title="Tony Hoare">C. A. R. Hoare</a> in his Oct 1980 <a href="/wiki/Turing_Award" title="Turing Award">Turing Award</a> Lecture<a href="#cite_note-71">[71]</a></li> <li>"[...] More than ever it will be required from an adequate programming tool that it assists, by structure, the programmer in the most difficult aspects of his job, viz. in the reliable creation of sophisticated programs. In this respect we fail to see how the language proposed here is a significant step forward: on the contrary, we feel that its implicit view of the programmer's task is very much the same as, say, ten years ago. This forces upon us the conclusion that, regarded as a programming tool, the language must be regarded as obsolete. [...]" 1968 Working Group minority report on 23 December 1968.<a href="#cite_note-72">[72]</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=47" title="Edit section: See also">edit</a>]</div> <style data-mw-deduplicate="TemplateStyles:r1184024115">.mw-parser-output .div-col{margin-top:0.3em;column-width:30em}.mw-parser-output .div-col-small{font-size:90%}.mw-parser-output .div-col-rules{column-rule:1px solid #aaa}.mw-parser-output .div-col dl,.mw-parser-output .div-col ol,.mw-parser-output .div-col ul{margin-top:0}.mw-parser-output .div-col li,.mw-parser-output .div-col dd{page-break-inside:avoid;break-inside:avoid-column}</style><div class="div-col" style="column-width: 22em;"> <ul><li><a href="/wiki/ALGOL_60" title="ALGOL 60">ALGOL 60</a></li> <li><a href="/wiki/ALGOL_Y" title="ALGOL Y">ALGOL Y</a></li> <li><a href="/wiki/ALGOL_N" title="ALGOL N">ALGOL N</a></li> <li><a href="/wiki/ALGOL_68C" title="ALGOL 68C">ALGOL 68C</a></li> <li><a href="/wiki/C_(programming_language)" title="C (programming language)">C (programming language)</a></li> <li><a href="/wiki/C%2B%2B" title="C++">C++</a></li> <li><a href="/wiki/Comparison_of_ALGOL_68_and_C%2B%2B" title="Comparison of ALGOL 68 and C++">Comparison of ALGOL 68 and C++</a></li> <li><a href="/wiki/Bourne_shell" title="Bourne shell">Bourne shell</a></li> <li><a href="/wiki/Bash_(Unix_shell)" title="Bash (Unix shell)">Bash (Unix shell)</a></li> <li><a href="/wiki/Steelman_language_requirements" title="Steelman language requirements">Steelman language requirements</a></li> <li><a href="/wiki/Ada_(programming_language)" title="Ada (programming language)">Ada (programming language)</a></li> <li><a href="/wiki/Python_(programming_language)" title="Python (programming language)">Python (programming language)</a></li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="References">References</h2>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=48" title="Edit section: References">edit</a>]</div> <div class="mw-heading mw-heading3"><h3 id="Citations">Citations</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=49" title="Edit section: Citations">edit</a>]</div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap mw-references-columns"><ol class="references"> <li id="cite_note-Wijngaarden_1976-1"><a href="#cite_ref-Wijngaarden_1976_1-0">^</a> <style data-mw-deduplicate="TemplateStyles:r1238218222">.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite id="CITEREFvan_WijngaardenMaillouxPeckKoster1976" class="citation book cs1 cs1-prop-interwiki-linked-name"><a href="/wiki/Adriaan_van_Wijngaarden" title="Adriaan van Wijngaarden">van Wijngaarden, Adriaan</a>; <a href="/wiki/Barry_James_Mailloux" class="mw-redirect" title="Barry James Mailloux">Mailloux, Barry James</a>; <a href="/wiki/John_Edward_Lancelot_Peck" class="mw-redirect" title="John Edward Lancelot Peck">Peck, John Edward Lancelot</a>; <a href="/wiki/Cornelis_Hermanus_Antonius_Koster" class="mw-redirect" title="Cornelis Hermanus Antonius Koster">Koster, Cornelis Hermanus Antonius</a>; <a href="https://fr.wikipedia.org/wiki/Michel_Sintzoff" class="extiw" title="fr:Michel Sintzoff">Sintzoff, Michel</a> [in French]; <a href="/wiki/Charles_Hodgson_Lindsey" class="mw-redirect" title="Charles Hodgson Lindsey">Lindsey, Charles Hodgson</a>; <a href="/wiki/Lambert_Guillaume_Louis_Th%C3%A9odore_Meertens" class="mw-redirect" title="Lambert Guillaume Louis Théodore Meertens">Meertens, Lambert Guillaume Louis Théodore</a>; Fisker, Richard G., eds. (1976). <a rel="nofollow" class="external text" href="http://web.eah-jena.de/~kleine/history/languages/algol68-revisedreport.pdf">Revised Report on the Algorithmic Language ALGOL 68</a> (PDF). <a href="/wiki/Springer-Verlag" class="mw-redirect" title="Springer-Verlag">Springer-Verlag</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-387-07592-1" title="Special:BookSources/978-0-387-07592-1"><bdi>978-0-387-07592-1</bdi></a>. <a href="/wiki/OCLC_(identifier)" class="mw-redirect" title="OCLC (identifier)">OCLC</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/oclc/1991170">1991170</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20190419223929/http://web.eah-jena.de/~kleine/history/languages/algol68-revisedreport.pdf">Archived</a> (PDF) from the original on 2019-04-19. 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"ALGOL 68 and Its Impact on the USSR and Russian Programming". 2014 Third International Conference on Computer Technology in Russia and in the Former Soviet Union. pp. 97–106. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1109%2FSoRuCom.2014.29">10.1109/SoRuCom.2014.29</a>. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-1-4799-1799-0" title="Special:BookSources/978-1-4799-1799-0"><bdi>978-1-4799-1799-0</bdi></a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:16097093">16097093</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=bookitem&rft.atitle=ALGOL+68+and+Its+Impact+on+the+USSR+and+Russian+Programming&rft.btitle=2014+Third+International+Conference+on+Computer+Technology+in+Russia+and+in+the+Former+Soviet+Union&rft.pages=97-106&rft.date=2014&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A16097093%23id-name%3DS2CID&rft_id=info%3Adoi%2F10.1109%2FSoRuCom.2014.29&rft.isbn=978-1-4799-1799-0&rft.aulast=Terekhov&rft.aufirst=Andrey&rfr_id=info%3Asid%2Fen.wikipedia.org%3AALGOL+68" class="Z3988"> </li> <li id="cite_note-16"><a href="#cite_ref-16">^</a> <a rel="nofollow" class="external free" href="http://toc.proceedings.com/25445webtoc.pdf">http://toc.proceedings.com/25445webtoc.pdf</a> "Алгол 68 и его влияние на программирование в СССР и России" – pages: 336 & 342 </li> <li id="cite_note-FOOTNOTELindsey1996-17"><a href="#cite_ref-FOOTNOTELindsey1996_17-0">^</a> <a href="#CITEREFLindsey1996">Lindsey 1996</a>. </li> <li id="cite_note-ahoa68-18">^ <a href="#cite_ref-ahoa68_18-0">a</a> <a href="#cite_ref-ahoa68_18-1">b</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLindsey1996" class="citation book cs1"><a href="/wiki/Charles_H._Lindsey" title="Charles H. Lindsey">Lindsey, Charles H.</a> (1996). Bergin, T. J.; Gibson, R. G. (eds.). A history of ALGOL 68. <a href="/wiki/History_of_Programming_Languages#HOPL_II" class="mw-redirect" title="History of Programming Languages">History of Programming Languages-II</a>. 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Retrieved 2005-08-27.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Archived+copy&rft_id=http%3A%2F%2Fwww.fh-jena.de%2F~kleine%2Fhistory%2Flanguages%2FAlgol68-RR-HardwareRepresentation.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AALGOL+68" class="Z3988"><code class="cs1-code">{{<a href="/wiki/Template:Cite_web" title="Template:Cite web">cite web</a>}}</code>: CS1 maint: archived copy as title (<a href="/wiki/Category:CS1_maint:_archived_copy_as_title" title="Category:CS1 maint: archived copy as title">link</a>) </li> <li id="cite_note-68"><a href="#cite_ref-68">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFC._H._A._Koster1993" class="citation book cs1">C. H. A. Koster (1993). The Making of Algol 68. 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March 1970. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20070930230048/http://archive.computerhistory.org/resources/text/algol/algol_bulletin/A31/P111.HTM">Archived</a> from the original on 2007-09-30. Retrieved 2007-03-01.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=ALGOL+Bulletin+%28referred+to+in+AB30.1.1.1%29&rft.date=1970-03&rft_id=http%3A%2F%2Farchive.computerhistory.org%2Fresources%2Ftext%2Falgol%2Falgol_bulletin%2FA31%2FP111.HTM&rfr_id=info%3Asid%2Fen.wikipedia.org%3AALGOL+68" class="Z3988"> </li> </ol></div></div> <div class="mw-heading mw-heading3"><h3 id="Works_cited">Works cited</h3>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=50" title="Edit section: Works cited">edit</a>]</div> <style data-mw-deduplicate="TemplateStyles:r1239549316">.mw-parser-output .refbegin{margin-bottom:0.5em}.mw-parser-output .refbegin-hanging-indents>ul{margin-left:0}.mw-parser-output .refbegin-hanging-indents>ul>li{margin-left:0;padding-left:3.2em;text-indent:-3.2em}.mw-parser-output .refbegin-hanging-indents ul,.mw-parser-output .refbegin-hanging-indents ul li{list-style:none}@media(max-width:720px){.mw-parser-output .refbegin-hanging-indents>ul>li{padding-left:1.6em;text-indent:-1.6em}}.mw-parser-output .refbegin-columns{margin-top:0.3em}.mw-parser-output .refbegin-columns ul{margin-top:0}.mw-parser-output .refbegin-columns li{page-break-inside:avoid;break-inside:avoid-column}@media screen{.mw-parser-output .refbegin{font-size:90%}}</style><div class="refbegin" style=""> <ul><li>Brailsford, D. F. and Walker, A. N., Introductory ALGOL 68 Programming, Ellis Horwood/Wiley, 1979</li> <li>Lindsey, C. H. and van der Meulen, S. G., Informal Introduction to ALGOL 68, North-Holland, 1971</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFLindsey1993" class="citation journal cs1">Lindsey, C. H. (1993-03-02). <a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F155360.155365">"A History of ALGOL 68"</a>. ACM SIGPLAN Notices. 28 (3): 97–132. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1145%2F155360.155365">10.1145/155360.155365</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=ACM+SIGPLAN+Notices&rft.atitle=A+History+of+ALGOL+68&rft.volume=28&rft.issue=3&rft.pages=97-132&rft.date=1993-03-02&rft_id=info%3Adoi%2F10.1145%2F155360.155365&rft.aulast=Lindsey&rft.aufirst=C.+H.&rft_id=https%3A%2F%2Fdoi.org%2F10.1145%252F155360.155365&rfr_id=info%3Asid%2Fen.wikipedia.org%3AALGOL+68" class="Z3988"></li> <li>McGettrick, A. D., ALGOL 68, A First and Second Course, Cambridge Univ. Press, 1978</li> <li>Peck, J. E. L., An ALGOL 68 Companion, Univ. of British Columbia, October 1971</li> <li>Tanenbaum, A. S., A Tutorial on ALGOL 68, Computing Surveys 8, 155-190, June 1976 and 9, 255-256, September 1977, <a rel="nofollow" class="external autonumber" href="http://vestein.arb-phys.uni-dortmund.de/~wb/RR/tanenbaum.pdf">[7]</a>[<a href="/wiki/Wikipedia:Link_rot" title="Wikipedia:Link rot">permanent dead link</a>‍]</li> <li>Woodward, P. M. and Bond, S. G., ALGOL 68-R Users<a href="/wiki/Sic" title="Sic">sic</a> Guide, London, Her Majesty's Stationery Office, 1972</li></ul> </div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2>[<a href="/w/index.php?title=ALGOL_68&action=edit&section=51" title="Edit section: External links">edit</a>]</div> <ul><li><a rel="nofollow" class="external text" href="http://www.softwarepreservation.org/projects/ALGOL/report/Algol68_revised_report-AB.pdf">Revised Report on the Algorithmic Language ALGOL 68</a> The official reference for users and implementors of the language (large pdf file, scanned from Algol Bulletin)</li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20150906170502/http://jmvdveer.home.xs4all.nl/algol68/report.html">Revised Report on the Algorithmic Language ALGOL 68</a> Hyperlinked HTML version of the Revised Report</li> <li><a rel="nofollow" class="external text" href="http://portal.acm.org/citation.cfm?id=356671">A Tutorial on Algol 68</a>, by <a href="/wiki/Andrew_S._Tanenbaum" title="Andrew S. Tanenbaum">Andrew S. Tanenbaum</a>, in Computing Surveys, Vol. 8, No. 2, June 1976, with <a rel="nofollow" class="external text" href="http://portal.acm.org/citation.cfm?id=356706">Corrigenda</a> (Vol. 9, No. 3, September 1977)</li> <li><a rel="nofollow" class="external text" href="https://jmvdveer.home.xs4all.nl/en.algol-68-genie.html">Algol 68 Genie – a GNU GPL Algol 68 compiler-interpreter</a></li> <li><a rel="nofollow" class="external text" href="http://algol68.sourceforge.net/">Open source ALGOL 68 implementations, on SourceForge</a></li> <li><a rel="nofollow" class="external text" href="http://www.fh-jena.de/~kleine/history/languages/Algol68-RR-HardwareRepresentation.pdf">Algol68 Standard Hardware representation (.pdf)</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20140102201013/http://www.fh-jena.de/~kleine/history/languages/Algol68-RR-HardwareRepresentation.pdf">Archived</a> 2014-01-02 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a></li> <li><a rel="nofollow" class="external text" href="http://www.computer-museum.ru/histsoft/algol68.htm">Из истории создания компилятора с Алгол 68</a></li> <li><a rel="nofollow" class="external text" href="http://www.computer-museum.ru/english/algol68.htm">Algol 68 – 25 Years in the USSR</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20060310003954/http://ant.tepkom.ru/newsite/disser/doc/Ruchlin.htm">Система программ динамической поддержки для транслятора с Алгол 68</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/19980220175804/http://cm.bell-labs.com/cm/cs/who/dmr/chist.html">C history with Algol68 heritage</a></li> <li>McJones, Paul, <a rel="nofollow" class="external text" href="http://www.softwarepreservation.org/projects/ALGOL/algol68impl">"Algol 68 implementations and dialects"</a>, Software Preservation Group, <a href="/wiki/Computer_History_Museum" title="Computer History Museum">Computer History Museum</a>, 2011-07-05</li> <li><a rel="nofollow" class="external text" href="https://archive.today/20150416164933/http://vintagebigblue.org/Compilerator/ALGOL68C/mvsAlgol68CCompile.php">Web enabled ALGOL 68 compiler for small experiments</a></li></ul> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul 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.navbox-group,.mw-parser-output .navbox-subgroup .navbox-title{background-color:#ddf}.mw-parser-output .navbox-subgroup .navbox-group,.mw-parser-output .navbox-subgroup .navbox-abovebelow{background-color:#e6e6ff}.mw-parser-output .navbox-even{background-color:#f7f7f7}.mw-parser-output .navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}</style></div><div role="navigation" class="navbox" aria-labelledby="ALGOL_programming" style="padding:3px"><table class="nowraplinks hlist mw-collapsible mw-collapsed navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1239400231">.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}</style><div class="navbar plainlinks hlist navbar-mini"><ul><li class="nv-view"><a href="/wiki/Template:ALGOL_programming" title="Template:ALGOL programming"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:ALGOL_programming" title="Template talk:ALGOL programming"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:ALGOL_programming" title="Special:EditPage/Template:ALGOL programming"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="ALGOL_programming" style="font-size:114%;margin:0 4em"><a href="/wiki/ALGOL" title="ALGOL">ALGOL</a> programming</div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Programming_language_implementation" title="Programming language implementation">Implementations</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Technical_standard" title="Technical standard">Technical standards</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ALGOL_58" title="ALGOL 58">ALGOL 58</a></li> <li><a href="/wiki/ALGOL_60" title="ALGOL 60">ALGOL 60</a></li> <li><a class="mw-selflink selflink">ALGOL 68</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Dialect_(computing)" class="mw-redirect" title="Dialect (computing)">Dialects</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ABC_ALGOL" title="ABC ALGOL">ABC ALGOL</a></li> <li><a href="/wiki/ALCOR" title="ALCOR">ALCOR</a></li> <li><a href="/wiki/ALGO" title="ALGO">ALGO</a></li> <li><a href="/wiki/ALGOL_68C" title="ALGOL 68C">ALGOL 68C</a></li> <li><a href="/wiki/ALGOL_68-R" title="ALGOL 68-R">ALGOL 68-R</a></li> <li><a href="/wiki/ALGOL_68RS" title="ALGOL 68RS">ALGOL 68RS</a> (<a href="/wiki/ELLA_(programming_language)" title="ELLA (programming language)">ELLA</a>)</li> <li><a href="/wiki/ALGOL_68S" title="ALGOL 68S">ALGOL 68S</a></li> <li><a href="/wiki/ALGOL_N" title="ALGOL N">ALGOL N</a></li> <li><a href="/wiki/ALGOL_W" title="ALGOL W">ALGOL W</a></li> <li><a href="/wiki/ALGOL_X" title="ALGOL X">ALGOL X</a></li> <li><a href="/wiki/Atlas_Autocode" title="Atlas Autocode">Atlas Autocode</a> (<a href="/wiki/Edinburgh_IMP" title="Edinburgh IMP">Edinburgh IMP</a>)</li> <li><a href="/wiki/Burroughs_Large_Systems#ALGOL" title="Burroughs Large Systems">Burroughs ALGOL</a></li> <li><a href="/wiki/CORAL" title="CORAL">CORAL</a> 66</li> <li><a href="/wiki/Dartmouth_ALGOL_30" title="Dartmouth ALGOL 30">Dartmouth ALGOL 30</a></li> <li><a href="/wiki/DASK" title="DASK">DASK</a> ALGOL</li> <li><a href="/wiki/DG/L" title="DG/L">DG/L</a></li> <li><a href="/wiki/Elliott_ALGOL" title="Elliott ALGOL">Elliott ALGOL</a></li> <li><a href="/wiki/Executive_Systems_Problem_Oriented_Language" title="Executive Systems Problem Oriented Language">Executive Systems Problem Oriented Language</a> (ESPOL) → New Executive Programming Language (<a href="/wiki/NEWP" title="NEWP">NEWP</a>)</li> <li><a href="/wiki/FLACC" title="FLACC">FLACC</a></li> <li><a href="/wiki/IMP_(programming_language)" title="IMP (programming language)">IMP</a></li> <li><a href="/wiki/JOVIAL" title="JOVIAL">JOVIAL</a></li> <li><a href="/wiki/English_Electric_KDF9" title="English Electric KDF9">Kidsgrove</a> Algol</li> <li><a href="/wiki/MAD_(programming_language)" title="MAD (programming language)">MAD</a></li> <li><a href="/wiki/Mary_(programming_language)" title="Mary (programming language)">Mary</a></li> <li><a href="/wiki/NELIAC" title="NELIAC">NELIAC</a></li> <li><a href="/wiki/RTL/2" title="RTL/2">RTL/2</a></li> <li><a href="/wiki/S-algol" title="S-algol">S-algol</a>, <a href="/wiki/PS-algol" title="PS-algol">PS-algol</a>, <a href="/wiki/Napier88" title="Napier88">Napier88</a></li> <li><a href="/wiki/Simula" title="Simula">Simula</a></li> <li>Small Machine ALGOL Like Language (<a href="/wiki/SMALL" title="SMALL">SMALL</a>)</li> <li><a href="/wiki/SMIL_(computer)" title="SMIL (computer)">SMIL</a> ALGOL</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Formalism_(philosophy_of_mathematics)" title="Formalism (philosophy of mathematics)">Formalisms</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Jensen%27s_device" title="Jensen's device">Jensen's device</a></li> <li><a href="/wiki/Van_Wijngaarden_grammar" title="Van Wijngaarden grammar">Van Wijngaarden grammar</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Community_of_practice" title="Community of practice">Community</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Organizations</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Professional_association" title="Professional association">Professional associations</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/ALCOR" title="ALCOR">ALCOR</a> Group</li> <li><a href="/wiki/Association_for_Computing_Machinery" title="Association for Computing Machinery">Association for Computing Machinery</a> (ACM)</li> <li><a href="/wiki/BSI_Group" title="BSI Group">BSI Group</a></li> <li><a href="/wiki/GOST" title="GOST">Euro-Asian Council for Standardization, Metrology and Certification</a> (EASC)</li> <li><a href="/wiki/International_Federation_for_Information_Processing" title="International Federation for Information Processing">International Federation for Information Processing</a> (IFIP) <a href="/wiki/IFIP_Working_Group_2.1" title="IFIP Working Group 2.1">IFIP Working Group 2.1</a></li> <li><a href="/wiki/Gesellschaft_f%C3%BCr_Angewandte_Mathematik_und_Mechanik" title="Gesellschaft für Angewandte Mathematik und Mechanik">Society of Applied Mathematics and Mechanics</a> (GAMM)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Business</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Burroughs_Corporation" title="Burroughs Corporation">Burroughs Corporation</a></li> <li><a href="/wiki/Elliott_Brothers_(computer_company)" title="Elliott Brothers (computer company)">Elliott Brothers</a></li> <li><a href="/wiki/Regnecentralen" title="Regnecentralen">Regnecentralen</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Education</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Case_Western_Reserve_University" title="Case Western Reserve University">Case Institute of Technology</a></li> <li><a href="/wiki/University_of_Edinburgh" title="University of Edinburgh">University of Edinburgh</a></li> <li><a href="/wiki/University_of_St_Andrews" title="University of St Andrews">University of St Andrews</a></li> <li><a href="/wiki/Manchester_University" class="mw-redirect" title="Manchester University">Manchester University</a></li> <li><a href="/wiki/Massachusetts_Institute_of_Technology" title="Massachusetts Institute of Technology">Massachusetts Institute of Technology</a> (MIT)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Government</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Royal_Radar_Establishment" title="Royal Radar Establishment">Royal Radar Establishment</a> (RRE)</li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">People</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/ALGOL_58" title="ALGOL 58">ALGOL 58</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><td colspan="2" class="navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/John_Backus" title="John Backus">John Backus</a></li> <li><a href="/wiki/Friedrich_L._Bauer" title="Friedrich L. Bauer">Friedrich L. Bauer</a></li> <li><a href="/wiki/Hermann_Bottenbruch" title="Hermann Bottenbruch">Hermann Bottenbruch</a></li> <li><a href="/wiki/Charles_Katz" title="Charles Katz">Charles Katz</a></li> <li><a href="/wiki/Alan_Perlis" title="Alan Perlis">Alan Perlis</a></li> <li><a href="/wiki/Heinz_Rutishauser" title="Heinz Rutishauser">Heinz Rutishauser</a></li> <li><a href="/wiki/Klaus_Samelson" title="Klaus Samelson">Klaus Samelson</a></li> <li><a href="/wiki/Joseph_Henry_Wegstein" title="Joseph Henry Wegstein">Joseph Henry Wegstein</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/MAD_(programming_language)" title="MAD (programming language)">MAD</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Bruce_Arden" title="Bruce Arden">Bruce Arden</a></li> <li><a href="/wiki/Bernard_Galler" title="Bernard Galler">Bernard Galler</a></li> <li><a href="/wiki/Robert_M._Graham_(computer_scientist)" title="Robert M. Graham (computer scientist)">Robert M. Graham</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/ALGOL_60" title="ALGOL 60">ALGOL 60</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><td colspan="2" class="navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li>Backus^</li> <li><a href="/wiki/Roland_Carl_Backhouse" title="Roland Carl Backhouse">Roland Carl Backhouse</a></li> <li>Bauer^</li> <li><a href="/wiki/Richard_Bird_(computer_scientist)" title="Richard Bird (computer scientist)">Richard Bird</a></li> <li><a href="/wiki/Stephen_R._Bourne" title="Stephen R. Bourne">Stephen R. Bourne</a></li> <li><a href="/wiki/Edsger_W._Dijkstra" title="Edsger W. Dijkstra">Edsger W. Dijkstra</a></li> <li><a href="/wiki/Andrey_Ershov" class="mw-redirect" title="Andrey Ershov">Andrey Ershov</a></li> <li><a href="/wiki/Robert_W._Floyd" title="Robert W. Floyd">Robert W. Floyd</a></li> <li><a href="/wiki/Jeremy_Gibbons" title="Jeremy Gibbons">Jeremy Gibbons</a></li> <li>Julien Green</li> <li><a href="/wiki/David_Gries" title="David Gries">David Gries</a></li> <li><a href="/wiki/Eric_Hehner" title="Eric Hehner">Eric Hehner</a></li> <li><a href="/wiki/Tony_Hoare" title="Tony Hoare">Tony Hoare</a></li> <li><a href="/wiki/J%C3%B8rn_Jensen" title="Jørn Jensen">Jørn Jensen</a></li> <li>Katz^</li> <li><a href="/wiki/Peter_Landin" title="Peter Landin">Peter Landin</a></li> <li><a href="/wiki/Tom_Maibaum" title="Tom Maibaum">Tom Maibaum</a></li> <li><a href="/wiki/Conor_McBride" title="Conor McBride">Conor McBride</a></li> <li><a href="/wiki/John_McCarthy_(computer_scientist)" title="John McCarthy (computer scientist)">John McCarthy</a></li> <li><a href="/wiki/Carroll_Morgan_(computer_scientist)" title="Carroll Morgan (computer scientist)">Carroll Morgan</a></li> <li><a href="/wiki/Peter_Naur" title="Peter Naur">Peter Naur</a></li> <li><a href="/wiki/Maurice_Nivat" title="Maurice Nivat">Maurice Nivat</a></li> <li><a href="/wiki/John_E._L._Peck" title="John E. L. Peck">John E. L. Peck</a></li> <li>Perlis^</li> <li><a href="/wiki/Brian_Randell" title="Brian Randell">Brian Randell</a></li> <li>Rutishauser^</li> <li>Samelson^</li> <li><a href="/wiki/Jacob_T._Schwartz" title="Jacob T. Schwartz">Jacob T. Schwartz</a></li> <li><a href="/wiki/Micha_Sharir" title="Micha Sharir">Micha Sharir</a></li> <li><a href="/wiki/David_Turner_(computer_scientist)" title="David Turner (computer scientist)">David Turner</a></li> <li><a href="/wiki/Bernard_Vauquois" title="Bernard Vauquois">Bernard Vauquois</a></li> <li><a href="/wiki/Eiiti_Wada" title="Eiiti Wada">Eiiti Wada</a></li> <li>Wegstein^</li> <li><a href="/wiki/Adriaan_van_Wijngaarden" title="Adriaan van Wijngaarden">Adriaan van Wijngaarden</a></li> <li><a href="/wiki/Mike_Woodger" title="Mike Woodger">Mike Woodger</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Simula" title="Simula">Simula</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Ole-Johan_Dahl" title="Ole-Johan Dahl">Ole-Johan Dahl</a></li> <li><a href="/wiki/Kristen_Nygaard" title="Kristen Nygaard">Kristen Nygaard</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a class="mw-selflink selflink">ALGOL 68</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li>Bauer^</li> <li><a href="/wiki/Susan_G._Bond" title="Susan G. Bond">Susan G. Bond</a></li> <li>Bourne^</li> <li><a href="/wiki/Robert_Dewar" title="Robert Dewar">Robert Dewar</a></li> <li>Dijkstra^</li> <li><a href="https://de.wikipedia.org/wiki/Gerhard_Goos" class="extiw" title="de:Gerhard Goos">Gerhard Goos</a></li> <li><a href="/wiki/Michael_Guy" title="Michael Guy">Michael Guy</a></li> <li>Hoare^</li> <li><a href="/wiki/Cornelis_H._A._Koster" title="Cornelis H. A. Koster">Cornelis H. A. Koster</a></li> <li><a href="/wiki/Peter_Landin" title="Peter Landin">Peter Landin</a></li> <li><a href="/wiki/Charles_H._Lindsey" title="Charles H. Lindsey">Charles H. Lindsey</a></li> <li><a href="/wiki/Barry_J._Mailloux" title="Barry J. Mailloux">Barry J. Mailloux</a></li> <li>McCarthy^</li> <li><a href="/wiki/Lambert_Meertens" title="Lambert Meertens">Lambert Meertens</a></li> <li>Naur^</li> <li>Peck^</li> <li><a href="/wiki/Willem_van_der_Poel" title="Willem van der Poel">Willem van der Poel</a></li> <li>Randell^</li> <li><a href="/wiki/Douglas_T._Ross" title="Douglas T. Ross">Douglas T. Ross</a></li> <li>Samelson^</li> <li><a href="/wiki/Michel_Sintzoff" title="Michel Sintzoff">Michel Sintzoff</a></li> <li>van Wijngaarden^</li> <li><a href="/wiki/Niklaus_Wirth" title="Niklaus Wirth">Niklaus Wirth</a></li> <li>Woodger^</li> <li><a href="/wiki/Philip_Woodward" title="Philip Woodward">Philip Woodward</a></li> <li><a href="/wiki/Nobuo_Yoneda" title="Nobuo Yoneda">Nobuo Yoneda</a></li></ul> </div></td></tr></tbody></table><div> <ul><li><a href="/wiki/Hal_Abelson" title="Hal Abelson">Hal Abelson</a></li> <li><a href="/wiki/John_Barnes_(computer_scientist)" title="John Barnes (computer scientist)">John Barnes</a></li> <li><a href="/wiki/Tony_Brooker" title="Tony Brooker">Tony Brooker</a></li> <li><a href="/wiki/Ron_Morrison" title="Ron Morrison">Ron Morrison</a></li> <li><a href="/wiki/Peter_O%27Hearn" title="Peter O'Hearn">Peter O'Hearn</a></li> <li><a href="/wiki/John_C._Reynolds" title="John C. Reynolds">John C. Reynolds</a></li></ul></div></td></tr></tbody></table><div> <ul><li><a href="/wiki/ALGOL_Bulletin" title="ALGOL Bulletin">ALGOL Bulletin</a></li></ul></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Comparison</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <li><a href="/wiki/ALGOL_58#ALGOL_58's_influence_on_ALGOL_60" title="ALGOL 58">ALGOL 58 influence on ALGOL 60</a></li> <li><a class="mw-selflink-fragment" href="#Comparisons_with_other_languages">ALGOL 68 to other languages</a></li> <li><a href="/wiki/Comparison_of_ALGOL_68_and_C%2B%2B" title="Comparison of ALGOL 68 and C++">ALGOL 68 to C++</a></li> </div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div> <ul><li>^ = full name and link in prior ALGOL version above <img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /> <a href="/wiki/Category:Algol_programming_language_family" title="Category:Algol programming language family">Category: ALGOL</a> <img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/16px-Symbol_category_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/23px-Symbol_category_class.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/9/96/Symbol_category_class.svg/31px-Symbol_category_class.svg.png 2x" data-file-width="180" data-file-height="185" /> <a href="/wiki/Category:ALGOL_60" title="Category:ALGOL 60">Category: ALGOL 60</a></li></ul> </div></td></tr></tbody></table></div> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236075235"></div><div role="navigation" class="navbox authority-control" aria-label="Navbox" style="padding:3px"><table class="nowraplinks hlist navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Help:Authority_control" title="Help:Authority control">Authority control databases</a>: National <a href="https://www.wikidata.org/wiki/Q2166735#identifiers" title="Edit this at Wikidata"><img alt="Edit this at Wikidata" src="//upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/10px-OOjs_UI_icon_edit-ltr-progressive.svg.png" decoding="async" width="10" height="10" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/15px-OOjs_UI_icon_edit-ltr-progressive.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/20px-OOjs_UI_icon_edit-ltr-progressive.svg.png 2x" data-file-width="20" data-file-height="20" /></a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"><ul><li><a rel="nofollow" class="external text" href="https://d-nb.info/gnd/4141871-2">Germany</a></li></ul></div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1" alt="" width="1" height="1" style="border: none; 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