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href="#Minimalism"> <div class="vector-toc-text"> 2.1 Minimalism </div> </a> <ul id="toc-Minimalism-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Lexical_scope" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Lexical_scope"> <div class="vector-toc-text"> 2.2 Lexical scope </div> </a> <ul id="toc-Lexical_scope-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Lambda_calculus" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Lambda_calculus"> <div class="vector-toc-text"> 2.3 Lambda calculus </div> </a> <ul id="toc-Lambda_calculus-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Block_structure" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Block_structure"> <div class="vector-toc-text"> 2.4 Block structure </div> </a> <ul id="toc-Block_structure-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Proper_tail_recursion" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Proper_tail_recursion"> <div class="vector-toc-text"> 2.5 Proper tail recursion </div> </a> <ul id="toc-Proper_tail_recursion-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-First-class_continuations" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#First-class_continuations"> <div class="vector-toc-text"> 2.6 First-class continuations </div> </a> <ul id="toc-First-class_continuations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Shared_namespace_for_procedures_and_variables" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Shared_namespace_for_procedures_and_variables"> <div class="vector-toc-text"> 2.7 Shared namespace for procedures and variables </div> </a> <ul id="toc-Shared_namespace_for_procedures_and_variables-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Implementation_standards" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Implementation_standards"> <div class="vector-toc-text"> 3 Implementation standards </div> </a> <button aria-controls="toc-Implementation_standards-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Implementation standards subsection </button> <ul id="toc-Implementation_standards-sublist" class="vector-toc-list"> <li id="toc-Numerical_tower" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Numerical_tower"> <div class="vector-toc-text"> 3.1 Numerical tower </div> </a> <ul id="toc-Numerical_tower-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Delayed_evaluation" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Delayed_evaluation"> <div class="vector-toc-text"> 3.2 Delayed evaluation </div> </a> <ul id="toc-Delayed_evaluation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Order_of_evaluation_of_procedure_arguments" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Order_of_evaluation_of_procedure_arguments"> <div class="vector-toc-text"> 3.3 Order of evaluation of procedure arguments </div> </a> <ul id="toc-Order_of_evaluation_of_procedure_arguments-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Hygienic_macros" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Hygienic_macros"> <div class="vector-toc-text"> 3.4 Hygienic macros </div> </a> <ul id="toc-Hygienic_macros-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Environments_and_eval" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Environments_and_eval"> <div class="vector-toc-text"> 3.5 Environments and eval </div> </a> <ul id="toc-Environments_and_eval-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Treatment_of_non-Boolean_values_in_Boolean_expressions" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Treatment_of_non-Boolean_values_in_Boolean_expressions"> <div class="vector-toc-text"> 3.6 Treatment of non-Boolean values in Boolean expressions </div> </a> <ul id="toc-Treatment_of_non-Boolean_values_in_Boolean_expressions-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Disjointness_of_primitive_datatypes" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Disjointness_of_primitive_datatypes"> <div class="vector-toc-text"> 3.7 Disjointness of primitive datatypes </div> </a> <ul id="toc-Disjointness_of_primitive_datatypes-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Equivalence_predicates" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Equivalence_predicates"> <div class="vector-toc-text"> 3.8 Equivalence predicates </div> </a> <ul id="toc-Equivalence_predicates-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Comments" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Comments"> <div class="vector-toc-text"> 3.9 Comments </div> </a> <ul id="toc-Comments-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Input/output" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Input/output"> <div class="vector-toc-text"> 3.10 Input/output </div> </a> <ul id="toc-Input/output-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Redefinition_of_standard_procedures" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Redefinition_of_standard_procedures"> <div class="vector-toc-text"> 3.11 Redefinition of standard procedures </div> </a> <ul id="toc-Redefinition_of_standard_procedures-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Nomenclature_and_naming_conventions" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Nomenclature_and_naming_conventions"> <div class="vector-toc-text"> 3.12 Nomenclature and naming conventions </div> </a> <ul id="toc-Nomenclature_and_naming_conventions-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Review_of_standard_forms_and_procedures" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Review_of_standard_forms_and_procedures"> <div class="vector-toc-text"> 4 Review of standard forms and procedures </div> </a> <button aria-controls="toc-Review_of_standard_forms_and_procedures-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> Toggle Review of standard forms and procedures subsection </button> <ul id="toc-Review_of_standard_forms_and_procedures-sublist" class="vector-toc-list"> <li id="toc-Standard_forms" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Standard_forms"> <div class="vector-toc-text"> 4.1 Standard forms </div> </a> <ul id="toc-Standard_forms-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Standard_procedures" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Standard_procedures"> <div class="vector-toc-text"> 4.2 Standard procedures </div> </a> <ul id="toc-Standard_procedures-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Scheme_Requests_for_Implementation" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Scheme_Requests_for_Implementation"> <div class="vector-toc-text"> 5 Scheme Requests for Implementation </div> </a> <ul id="toc-Scheme_Requests_for_Implementation-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Implementations" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Implementations"> <div class="vector-toc-text"> 6 Implementations </div> </a> <ul id="toc-Implementations-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Usage" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Usage"> <div class="vector-toc-text"> 7 Usage </div> </a> <ul id="toc-Usage-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> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Further_reading" class="vector-toc-list-item vector-toc-level-1"> <a class="vector-toc-link" href="#Further_reading"> <div class="vector-toc-text"> 10 Further reading </div> </a> <ul id="toc-Further_reading-sublist" class="vector-toc-list"> </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"> 11 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">Scheme (programming language)</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 48 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-48" aria-hidden="true" > 48 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%B3%D9%83%D9%8A%D9%85_(%D9%84%D8%BA%D8%A9_%D8%A8%D8%B1%D9%85%D8%AC%D8%A9)" title="سكيم (لغة برمجة) – Arabic" lang="ar" hreflang="ar" data-title="سكيم (لغة برمجة)" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target">العربية</a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/Scheme" title="Scheme – Azerbaijani" lang="az" hreflang="az" data-title="Scheme" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target">Azərbaycanca</a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%B8%E0%A7%8D%E0%A6%95%E0%A6%BF%E0%A6%AE_(%E0%A6%AA%E0%A7%8D%E0%A6%B0%E0%A7%8B%E0%A6%97%E0%A7%8D%E0%A6%B0%E0%A6%BE%E0%A6%AE%E0%A6%BF%E0%A6%82_%E0%A6%AD%E0%A6%BE%E0%A6%B7%E0%A6%BE)" title="স্কিম (প্রোগ্রামিং ভাষা) – Bangla" lang="bn" hreflang="bn" data-title="স্কিম (প্রোগ্রামিং ভাষা)" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target">বাংলা</a></li><li class="interlanguage-link interwiki-be mw-list-item"><a href="https://be.wikipedia.org/wiki/Scheme" title="Scheme – Belarusian" lang="be" hreflang="be" data-title="Scheme" data-language-autonym="Беларуская" data-language-local-name="Belarusian" class="interlanguage-link-target">Беларуская</a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/Scheme_(%D0%B5%D0%B7%D0%B8%D0%BA_%D0%B7%D0%B0_%D0%BF%D1%80%D0%BE%D0%B3%D1%80%D0%B0%D0%BC%D0%B8%D1%80%D0%B0%D0%BD%D0%B5)" title="Scheme (език за програмиране) – Bulgarian" lang="bg" hreflang="bg" data-title="Scheme (език за програмиране)" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target">Български</a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/Scheme" title="Scheme – Catalan" lang="ca" hreflang="ca" data-title="Scheme" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target">Català</a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Scheme" title="Scheme – Czech" lang="cs" hreflang="cs" data-title="Scheme" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target">Čeština</a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/Scheme" title="Scheme – Danish" lang="da" hreflang="da" data-title="Scheme" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target">Dansk</a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Scheme" title="Scheme – German" lang="de" hreflang="de" data-title="Scheme" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target">Deutsch</a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/Scheme" title="Scheme – Estonian" lang="et" hreflang="et" data-title="Scheme" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target">Eesti</a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/Scheme" title="Scheme – Greek" lang="el" hreflang="el" data-title="Scheme" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target">Ελληνικά</a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Scheme" title="Scheme – Spanish" lang="es" hreflang="es" data-title="Scheme" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target">Español</a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/Scheme" title="Scheme – Esperanto" lang="eo" hreflang="eo" data-title="Scheme" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target">Esperanto</a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%A7%D8%B3%DA%A9%DB%8C%D9%85_(%D8%B2%D8%A8%D8%A7%D9%86_%D8%A8%D8%B1%D9%86%D8%A7%D9%85%D9%87%E2%80%8C%D9%86%D9%88%DB%8C%D8%B3%DB%8C)" title="اسکیم (زبان برنامه‌نویسی) – Persian" lang="fa" hreflang="fa" data-title="اسکیم (زبان برنامه‌نویسی)" 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/Scheme" title="Scheme – French" lang="fr" hreflang="fr" data-title="Scheme" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target">Français</a></li><li class="interlanguage-link interwiki-fy mw-list-item"><a href="https://fy.wikipedia.org/wiki/Scheme" title="Scheme – Western Frisian" lang="fy" hreflang="fy" data-title="Scheme" data-language-autonym="Frysk" data-language-local-name="Western Frisian" class="interlanguage-link-target">Frysk</a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%8A%A4%ED%82%B4_(%ED%94%84%EB%A1%9C%EA%B7%B8%EB%9E%98%EB%B0%8D_%EC%96%B8%EC%96%B4)" title="스킴 (프로그래밍 언어) – Korean" lang="ko" hreflang="ko" data-title="스킴 (프로그래밍 언어)" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target">한국어</a></li><li class="interlanguage-link interwiki-hy mw-list-item"><a href="https://hy.wikipedia.org/wiki/Scheme" title="Scheme – Armenian" lang="hy" hreflang="hy" data-title="Scheme" data-language-autonym="Հայերեն" data-language-local-name="Armenian" class="interlanguage-link-target">Հայերեն</a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/Scheme" title="Scheme – Croatian" lang="hr" hreflang="hr" data-title="Scheme" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target">Hrvatski</a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Scheme" title="Scheme – Italian" lang="it" hreflang="it" data-title="Scheme" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target">Italiano</a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/Scheme" title="Scheme – Hebrew" lang="he" hreflang="he" data-title="Scheme" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target">עברית</a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/Scheme" title="Scheme – Lithuanian" lang="lt" hreflang="lt" data-title="Scheme" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target">Lietuvių</a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/Scheme" title="Scheme – Hungarian" lang="hu" hreflang="hu" data-title="Scheme" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target">Magyar</a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%B8%E0%B5%8D%E0%B4%95%E0%B5%80%E0%B4%82_(%E0%B4%AA%E0%B5%8D%E0%B4%B0%E0%B5%8B%E0%B4%97%E0%B5%8D%E0%B4%B0%E0%B4%BE%E0%B4%AE%E0%B4%BF%E0%B4%99%E0%B5%8D_%E0%B4%AD%E0%B4%BE%E0%B4%B7)" title="സ്കീം (പ്രോഗ്രാമിങ് ഭാഷ) – Malayalam" lang="ml" hreflang="ml" data-title="സ്കീം (പ്രോഗ്രാമിങ് ഭാഷ)" 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/Scheme" title="Scheme – Dutch" lang="nl" hreflang="nl" data-title="Scheme" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target">Nederlands</a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/Scheme" title="Scheme – Japanese" lang="ja" hreflang="ja" data-title="Scheme" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target">日本語</a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Scheme" title="Scheme – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="Scheme" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target">Norsk bokmål</a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/Scheme" title="Scheme – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="Scheme" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target">Norsk nynorsk</a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Scheme" title="Scheme – Polish" lang="pl" hreflang="pl" data-title="Scheme" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target">Polski</a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Scheme" title="Scheme – Portuguese" lang="pt" hreflang="pt" data-title="Scheme" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target">Português</a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Scheme_(limbaj_de_programare)" title="Scheme (limbaj de programare) – Romanian" lang="ro" hreflang="ro" data-title="Scheme (limbaj de programare)" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target">Română</a></li><li class="interlanguage-link interwiki-rue mw-list-item"><a href="https://rue.wikipedia.org/wiki/Scheme" title="Scheme – Rusyn" lang="rue" hreflang="rue" data-title="Scheme" data-language-autonym="Русиньскый" data-language-local-name="Rusyn" class="interlanguage-link-target">Русиньскый</a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/Scheme" title="Scheme – Russian" lang="ru" hreflang="ru" data-title="Scheme" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target">Русский</a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/Scheme_(programming_language)" title="Scheme (programming language) – Simple English" lang="en-simple" hreflang="en-simple" data-title="Scheme (programming language)" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target">Simple English</a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Scheme_(programovac%C3%AD_jazyk)" title="Scheme (programovací jazyk) – Slovak" lang="sk" hreflang="sk" data-title="Scheme (programovací jazyk)" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target">Slovenčina</a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/Scheme_(programski_jezik)" title="Scheme (programski jezik) – Slovenian" lang="sl" hreflang="sl" data-title="Scheme (programski jezik)" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target">Slovenščina</a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/Scheme_(programski_jezik)" title="Scheme (programski jezik) – Serbian" lang="sr" hreflang="sr" data-title="Scheme (programski jezik)" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target">Српски / srpski</a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/Scheme_(programski_jezik)" title="Scheme (programski jezik) – Serbo-Croatian" lang="sh" hreflang="sh" data-title="Scheme (programski jezik)" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target">Srpskohrvatski / српскохрватски</a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/Scheme" title="Scheme – Finnish" lang="fi" hreflang="fi" data-title="Scheme" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target">Suomi</a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/Scheme" title="Scheme – Swedish" lang="sv" hreflang="sv" data-title="Scheme" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target">Svenska</a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%87%E0%AE%9A%E0%AF%81%E0%AE%95%E0%AF%80%E0%AE%AE%E0%AF%8D" title="இசுகீம் – Tamil" lang="ta" hreflang="ta" data-title="இசுகீம்" data-language-autonym="தமிழ்" data-language-local-name="Tamil" class="interlanguage-link-target">தமிழ்</a></li><li class="interlanguage-link interwiki-tg mw-list-item"><a href="https://tg.wikipedia.org/wiki/Scheme" title="Scheme – Tajik" lang="tg" hreflang="tg" data-title="Scheme" 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/Scheme" title="Scheme – Turkish" lang="tr" hreflang="tr" data-title="Scheme" data-language-autonym="Türkçe" data-language-local-name="Turkish" class="interlanguage-link-target">Türkçe</a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/Scheme" title="Scheme – Ukrainian" lang="uk" hreflang="uk" data-title="Scheme" data-language-autonym="Українська" data-language-local-name="Ukrainian" class="interlanguage-link-target">Українська</a></li><li class="interlanguage-link interwiki-vi mw-list-item"><a href="https://vi.wikipedia.org/wiki/Scheme" title="Scheme – Vietnamese" lang="vi" hreflang="vi" data-title="Scheme" 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/Scheme_(%E7%A8%8B%E5%BC%8F%E8%AA%9E%E8%A8%80)" title="Scheme (程式語言) – Cantonese" lang="yue" hreflang="yue" data-title="Scheme (程式語言)" data-language-autonym="粵語" data-language-local-name="Cantonese" class="interlanguage-link-target">粵語</a></li><li class="interlanguage-link interwiki-bat-smg mw-list-item"><a href="https://bat-smg.wikipedia.org/wiki/Scheme" title="Scheme – Samogitian" lang="sgs" hreflang="sgs" data-title="Scheme" data-language-autonym="Žemaitėška" data-language-local-name="Samogitian" class="interlanguage-link-target">Žemaitėška</a></li><li class="interlanguage-link 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class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <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">Dialect of Lisp</div> <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 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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">Scheme</caption><tbody><tr><td colspan="2" class="infobox-image"><a href="/wiki/File:Lambda_lc.svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/3/39/Lambda_lc.svg/121px-Lambda_lc.svg.png" decoding="async" width="121" height="121" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/3/39/Lambda_lc.svg/182px-Lambda_lc.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/3/39/Lambda_lc.svg/242px-Lambda_lc.svg.png 2x" data-file-width="375" data-file-height="375" /></a></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/Functional_programming" title="Functional programming">functional</a>, <a href="/wiki/Imperative_programming" title="Imperative programming">imperative</a>, <a href="/wiki/Metaprogramming" title="Metaprogramming">meta</a></td></tr><tr><th scope="row" class="infobox-label">Family</th><td class="infobox-data"><a href="/wiki/Lisp_(programming_language)" title="Lisp (programming language)">Lisp</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/Guy_L._Steele" class="mw-redirect" title="Guy L. Steele">Guy L. Steele</a> <a href="/wiki/Gerald_Jay_Sussman" title="Gerald Jay Sussman">Gerald Jay Sussman</a></td></tr><tr><th scope="row" class="infobox-label">First appeared</th><td class="infobox-data">1975; 49 years ago (1975)</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;">R7RS / 2013; 11 years ago (2013)</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/Dynamic_typing" class="mw-redirect" title="Dynamic typing">Dynamic</a>, <a href="/wiki/Latent_typing" title="Latent typing">latent</a>, <a href="/wiki/Strong_typing" class="mw-redirect" title="Strong typing">strong</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)#Lexical_scoping_and_dynamic_scoping" title="Scope (computer science)">Lexical</a></td></tr><tr><th scope="row" class="infobox-label"><a href="/wiki/Filename_extension" title="Filename extension">Filename extensions</a></th><td class="infobox-data">.scm, .ss</td></tr><tr><th scope="row" class="infobox-label">Website</th><td class="infobox-data"><a rel="nofollow" class="external text" href="https://www.scheme.org/">www.scheme.org</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">Many (see <a href="/wiki/Category:Scheme_(programming_language)_implementations" title="Category:Scheme (programming language) implementations">Scheme implementations</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" title="ALGOL">ALGOL</a>, <a href="/wiki/Lisp_(programming_language)" title="Lisp (programming language)">Lisp</a>, <a href="/wiki/MDL_(programming_language)" title="MDL (programming language)">MDL</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/Clojure" title="Clojure">Clojure</a>, <a href="/wiki/Common_Lisp" title="Common Lisp">Common Lisp</a>, <a href="/wiki/Dylan_(programming_language)" title="Dylan (programming language)">Dylan</a>, <a href="/wiki/EuLisp" title="EuLisp">EuLisp</a>, <a href="/wiki/Haskell" title="Haskell">Haskell</a>, <a href="/wiki/Hop_(software)" title="Hop (software)">Hop</a>, <a href="/wiki/JavaScript" title="JavaScript">JavaScript</a>, <a href="/wiki/Julia_(programming_language)" title="Julia (programming language)">Julia</a>, <a href="/wiki/Lua_(programming_language)" title="Lua (programming language)">Lua</a>, <a href="/wiki/MultiLisp" title="MultiLisp">MultiLisp</a>, <a href="/wiki/Python_(programming_language)" title="Python (programming language)">Python</a>, <a href="/wiki/R_(programming_language)" title="R (programming language)">R</a>, <a href="/wiki/Racket_(programming_language)" title="Racket (programming language)">Racket</a>, <a href="/wiki/Ruby_(programming_language)" title="Ruby (programming language)">Ruby</a>, <a href="/wiki/Rust_(programming_language)" title="Rust (programming language)">Rust</a>,<a href="#cite_note-1">[1]</a> <a href="/wiki/S_(programming_language)" title="S (programming language)">S</a>, <a href="/wiki/Scala_(programming_language)" title="Scala (programming language)">Scala</a>, <a href="/wiki/T_(programming_language)" title="T (programming language)">T</a></td></tr><tr><td colspan="2" class="infobox-below hlist" style="border-top: 1px solid #aaa; padding-top: 3px;"> <ul><li><a href="/wiki/File:Wikibooks-logo-en-noslogan.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/16px-Wikibooks-logo-en-noslogan.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/24px-Wikibooks-logo-en-noslogan.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/32px-Wikibooks-logo-en-noslogan.svg.png 2x" data-file-width="400" data-file-height="400" /></a> <a href="https://en.wikibooks.org/wiki/Scheme" class="extiw" title="wikibooks:Scheme">Scheme</a> at Wikibooks</li></ul> </td></tr></tbody></table> Scheme is a <a href="/wiki/Programming_language_dialect" class="mw-redirect" title="Programming language dialect">dialect</a> of the <a href="/wiki/Lisp_(programming_language)" title="Lisp (programming language)">Lisp</a> family of <a href="/wiki/Programming_language" title="Programming language">programming languages</a>. Scheme was created during the 1970s at the <a href="/wiki/MIT_Computer_Science_and_Artificial_Intelligence_Laboratory" title="MIT Computer Science and Artificial Intelligence Laboratory">MIT Computer Science and Artificial Intelligence Laboratory</a> (MIT CSAIL) and released by its developers, <a href="/wiki/Guy_L._Steele" class="mw-redirect" title="Guy L. Steele">Guy L. Steele</a> and <a href="/wiki/Gerald_Jay_Sussman" title="Gerald Jay Sussman">Gerald Jay Sussman</a>, via a series of memos now known as the <a href="/wiki/Lambda_Papers" class="mw-redirect" title="Lambda Papers">Lambda Papers</a>. It was the first dialect of Lisp to choose <a href="/wiki/Scope_(computer_science)#Lexical_scoping_and_dynamic_scoping" title="Scope (computer science)">lexical scope</a> and the first to require implementations to perform <a href="/wiki/Tail-call_optimization" class="mw-redirect" title="Tail-call optimization">tail-call optimization</a>, giving stronger support for functional programming and associated techniques such as recursive algorithms. It was also one of the first programming languages to support <a href="/wiki/First-class_object" class="mw-redirect" title="First-class object">first-class</a> <a href="/wiki/Continuation" title="Continuation">continuations</a>. It had a significant influence on the effort that led to the development of <a href="/wiki/Common_Lisp" title="Common Lisp">Common Lisp</a>.<a href="#cite_note-cl_steele-2">[2]</a> The Scheme language is standardized in the official <a href="/wiki/Institute_of_Electrical_and_Electronics_Engineers" title="Institute of Electrical and Electronics Engineers">Institute of Electrical and Electronics Engineers</a> (IEEE) standard<a href="#cite_note-ieee1178-3">[3]</a> and a de facto standard called the Revisedn Report on the Algorithmic Language Scheme (RnRS). A widely implemented standard is R5RS (1998).<a href="#cite_note-r5rs-4">[4]</a> The most recently ratified standard of Scheme is "R7RS-small" (2013).<a href="#cite_note-r7rs-5">[5]</a> The more expansive and modular R6RS was ratified in 2007.<a href="#cite_note-r6rs-6">[6]</a> Both trace their descent from R5RS; the timeline below reflects the chronological order of ratification. <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History">History</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=1" title="Edit section: History">edit</a>]</div> <style data-mw-deduplicate="TemplateStyles:r1236090951">.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}</style><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/History_of_the_Scheme_programming_language" title="History of the Scheme programming language">History of the Scheme programming language</a></div> <div class="mw-heading mw-heading3"><h3 id="Origins">Origins</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=2" title="Edit section: Origins">edit</a>]</div> Scheme started in the 1970s as an attempt to understand <a href="/wiki/Carl_Hewitt" title="Carl Hewitt">Carl Hewitt</a>'s <a href="/wiki/Actor_model" title="Actor model">Actor model</a>, for which purpose Steele and Sussman wrote a "tiny Lisp interpreter" using <a href="/wiki/Maclisp" title="Maclisp">Maclisp</a> and then "added mechanisms for creating actors and sending messages".<a href="#cite_note-revisited-7">[7]</a> Scheme was originally called "Schemer", in the tradition of other <a href="/wiki/Lisp_(programming_language)" title="Lisp (programming language)">Lisp</a>-derived languages such as <a href="/wiki/Planner_(programming_language)" title="Planner (programming language)">Planner</a> or Conniver. The current name resulted from the authors' use of the <a href="/wiki/Incompatible_Timesharing_System" title="Incompatible Timesharing System">ITS operating system</a>, which limited filenames to two components of at most six characters each. Currently, "Schemer" is commonly used to refer to a Scheme programmer. <div class="mw-heading mw-heading3"><h3 id="R6RS">R6RS</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=3" title="Edit section: R6RS">edit</a>]</div> A new language standardization process began at the 2003 Scheme workshop, with the goal of producing an R6RS standard in 2006. This process broke with the earlier RnRS approach of unanimity. R6RS features a standard module system, allowing a split between the core language and <a href="/wiki/Library_(computing)" title="Library (computing)">libraries</a>. Several drafts of the R6RS specification were released, the final version being R5.97RS. A successful vote resulted in ratifying the new standard, announced on August 28, 2007.<a href="#cite_note-r6rs-6">[6]</a> Currently the newest releases of various Scheme implementations<a href="#cite_note-rs6s_Implementations-8">[8]</a> support the R6RS standard. There is a portable reference implementation of the proposed implicitly phased libraries for R6RS, called psyntax, which loads and bootstraps itself properly on various older Scheme implementations.<a href="#cite_note-psyntax-9">[9]</a> A feature of R6RS is the record-type descriptor (RTD). When an RTD is created and used, the record type representation can show the memory layout. It also calculated object field bit mask and mutable Scheme object field bit masks, and helped the garbage collector know what to do with the fields without traversing the whole fields list that are saved in the RTD. RTD allows users to expand the basic RTD to create a new record system.<a href="#cite_note-10">[10]</a> R6RS introduces numerous significant changes to the language.<a href="#cite_note-r6rs_Language_changes-11">[11]</a> The source code is now specified in <a href="/wiki/Unicode" title="Unicode">Unicode</a>, and a large subset of Unicode characters may now appear in Scheme symbols and <a href="/wiki/Identifier" title="Identifier">identifiers</a>, and there are other minor changes to the lexical rules. Character data is also now specified in Unicode. Many standard procedures have been moved to the new standard libraries, which themselves form a large expansion of the standard, containing procedures and syntactic forms that were formerly not part of the standard. A new module system has been introduced, and systems for exception handling are now standardized. Syntax-rules has been replaced with a more expressive syntactic abstraction facility (syntax-case) which allows the use of all of Scheme at macro expansion time. Compliant implementations are now required to support Scheme's full <a href="/wiki/Numerical_tower" title="Numerical tower">numeric tower</a>, and the semantics of numbers have been expanded, mainly in the direction of support for the <a href="/wiki/IEEE_754-1985" title="IEEE 754-1985">IEEE 754</a> standard for floating point numerical representation. <div class="mw-heading mw-heading3"><h3 id="R7RS">R7RS</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=4" title="Edit section: R7RS">edit</a>]</div> The R6RS standard has caused controversy because some see it as a departure from the minimalist philosophy.<a href="#cite_note-r6rs_electorate-12">[12]</a><a href="#cite_note-r6rs_feeley-13">[13]</a> In August 2009, the Scheme Steering Committee, which oversees the standardization process, announced its intention to recommend splitting Scheme into two languages: a large modern programming language for programmers; and a small version, a subset of the large version retaining the minimalism praised by educators and casual implementors.<a href="#cite_note-position_paper-14">[14]</a> Two working groups were created to work on these two new versions of Scheme. The Scheme Reports Process site has links to the working groups' charters, public discussions and issue tracking system. The ninth draft of R7RS (small language) was made available on April 15, 2013.<a href="#cite_note-r7rs-draft-9-15">[15]</a> A vote ratifying this draft closed on May 20, 2013,<a href="#cite_note-r7rs_clinger-16">[16]</a> and the final report has been available since August 6, 2013, describing "the 'small' language of that effort: therefore it cannot be considered in isolation as the successor to R6RS".<a href="#cite_note-r7rs-5">[5]</a> <table class="toccolours" style="font-size:88%"> <caption style="font-size:112%"><style data-mw-deduplicate="TemplateStyles:r1045256916">.mw-parser-output .navbar-header{text-align:center;position:relative;white-space:nowrap}.mw-parser-output .navbar-header .navbar{position:absolute;right:0;top:0;margin:0 5px}</style><div class="navbar-header">Timeline of Lisp dialects<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:Lisp" title="Template:Lisp"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Lisp" title="Template talk:Lisp"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Lisp" title="Special:EditPage/Template:Lisp"><abbr title="Edit this template">e</abbr></a></li></ul></div></div> </caption> <tbody><tr style="background:lavender;"> <th width="7%">1958 </th> <th width="7%">1960 </th> <th width="7%">1965 </th> <th width="7%">1970 </th> <th width="7%">1975 </th> <th width="7%">1980 </th> <th width="7%">1985 </th> <th width="7%">1990 </th> <th width="7%">1995 </th> <th width="7%">2000 </th> <th width="7%">2005 </th> <th width="7%">2010 </th> <th width="8%">2015 </th> <th width="8%">2020 </th></tr> <tr> <th align="left" colspan="3" style="background:lightgray"> LISP 1, 1.5, <a href="/wiki/LISP_2" title="LISP 2">LISP 2(abandoned)</a> </th> <td colspan="10"> </td></tr> <tr> <td colspan="2"> </td> <th align="left" colspan="5" style="background:lightgray"> <a href="/wiki/Maclisp" title="Maclisp">Maclisp</a> </th> <td colspan="6"> </td></tr> <tr> <td colspan="3"> </td> <th align="left" colspan="5" style="background:lightgray"> <a href="/wiki/Interlisp" title="Interlisp">Interlisp</a> </th> <td colspan="5"> </td></tr> <tr> <td colspan="3"> </td> <th align="left" colspan="2" style="background:lightgray"> <a href="/wiki/MDL_(programming_language)" title="MDL (programming language)">MDL</a> </th> <td colspan="5"> </td></tr> <tr> <td colspan="4"> </td> <th align="left" colspan="5" style="background:lightgray"> <a href="/wiki/Lisp_Machine_Lisp" title="Lisp Machine Lisp">Lisp Machine Lisp</a> </th> <td colspan="4"> </td></tr> <tr> <td colspan="4"> </td> <th align="left" colspan="4" style="background:lightgray"> <a class="mw-selflink selflink">Scheme</a> </th> <th align="left" colspan="2" style="background:lightgray"> R5RS </th> <th align="left" colspan="1" style="background:lightgray"> R6RS </th> <th align="left" colspan="3" style="background:lightgray"> R7RS small </th></tr> <tr> <td colspan="4"> </td> <th align="left" colspan="2" style="background:lightgray"> <a href="/wiki/NIL_(programming_language)" title="NIL (programming language)">NIL</a> </th></tr> <tr> <td colspan="5"> </td> <th align="left" colspan="2" style="background:lightgray"> <a href="/wiki/Z-machine#ZIL_(Zork_Implementation_Language)" title="Z-machine">ZIL (Zork Implementation Language)</a> </th></tr> <tr> <td colspan="5"> </td> <th align="left" colspan="2" style="background:lightgray"> <a href="/wiki/Franz_Lisp" title="Franz Lisp">Franz Lisp</a> </th></tr> <tr> <td colspan="5"> </td> <th align="left" colspan="2" style="background:lightgray"> <a href="/wiki/Common_Lisp" title="Common Lisp">Common Lisp</a> </th> <th align="left" colspan="7" style="background:lightgray"> ANSI standard </th></tr> <tr> <td colspan="5"> </td> <th align="left" colspan="9" style="background:lightgray"> <a href="/wiki/Le_Lisp" title="Le Lisp">Le Lisp</a> </th></tr> <tr> <td colspan="5"> </td> <th align="left" colspan="11" style="background:lightgray"> <a href="/wiki/MIT_Scheme" class="mw-redirect" title="MIT Scheme">MIT Scheme</a> </th></tr> <tr> <td colspan="5"> </td> <th align="left" colspan="4" style="background:lightgray"> <a href="/wiki/XLISP" title="XLISP">XLISP</a> </th></tr> <tr> <td colspan="6"> </td> <th align="left" colspan="3" style="background:lightgray"> <a href="/wiki/T_(programming_language)" title="T (programming language)">T</a> </th> <td colspan="4"> </td></tr> <tr> <td colspan="6"> </td> <th align="left" colspan="8" style="background:lightgray"> <a href="/wiki/Chez_Scheme" title="Chez Scheme">Chez Scheme</a> </th></tr> <tr> <td colspan="6"> </td> <th align="left" colspan="8" style="background:lightgray"> <a href="/wiki/Emacs_Lisp" title="Emacs Lisp">Emacs Lisp</a> </th></tr> <tr> <td colspan="6"> </td> <th align="left" colspan="8" style="background:lightgray"> <a href="/wiki/AutoLISP" title="AutoLISP">AutoLISP</a> </th></tr> <tr> <td colspan="6"> </td> <th align="left" colspan="8" style="background:lightgray"> <a href="/wiki/PicoLisp" title="PicoLisp">PicoLisp</a> </th></tr> <tr> <td colspan="6"> </td> <th align="left" colspan="8" style="background:lightgray"> <a href="/wiki/Gambit_(Scheme_implementation)" title="Gambit (Scheme implementation)">Gambit</a> </th></tr> <tr> <td colspan="7"> </td> <th align="left" colspan="6" style="background:lightgray"> <a href="/wiki/EuLisp" title="EuLisp">EuLisp</a> </th></tr> <tr> <td colspan="7"> </td> <th align="left" colspan="8" style="background:lightgray"> <a href="/wiki/ISLISP" title="ISLISP">ISLISP</a> </th></tr> <tr> <td colspan="7"> </td> <th align="left" colspan="8" style="background:lightgray"> <a href="/wiki/OpenLisp" title="OpenLisp">OpenLisp</a> </th></tr> <tr> <td colspan="7"> </td> <th align="left" colspan="4" style="background:lightgray"> <a href="/wiki/PLT_Scheme" class="mw-redirect" title="PLT Scheme">PLT Scheme</a> </th> <th align="left" colspan="3" style="background:lightgray"> <a href="/wiki/Racket_(programming_language)" title="Racket (programming language)">Racket</a> </th></tr> <tr> <td colspan="7"> </td> <th align="left" colspan="7" style="background:lightgray"> <a href="/wiki/NewLISP" title="NewLISP">newLISP</a> </th></tr> <tr> <td colspan="7"> </td> <th align="left" colspan="7" style="background:lightgray"> <a href="/wiki/GNU_Guile" title="GNU Guile">GNU Guile</a> </th></tr> <tr> <td colspan="9"> </td> <th align="left" colspan="5" style="background:lightgray"> <a href="/wiki/AutoLISP" title="AutoLISP">Visual LISP</a> </th></tr> <tr> <td colspan="10"> </td> <th align="left" colspan="4" style="background:lightgray"> <a href="/wiki/Clojure" title="Clojure">Clojure</a> </th></tr> <tr> <td colspan="10"> </td> <th align="left" colspan="4" style="background:lightgray"> <a href="/wiki/Arc_(programming_language)" title="Arc (programming language)">Arc</a> </th></tr> <tr> <td colspan="10"> </td> <th align="left" colspan="4" style="background:lightgray"> <a href="/wiki/LFE_(programming_language)" title="LFE (programming language)">LFE</a> </th></tr> <tr> <td colspan="11"> </td> <th align="left" colspan="3" style="background:lightgray"> <a href="/wiki/Hy_(programming_language)" title="Hy (programming language)">Hy</a> </th></tr> <tr> <td colspan="13"> </td> <th align="left" colspan="3" style="background:lightgray"> <a href="/w/index.php?title=Chialisp&action=edit&redlink=1" class="new" title="Chialisp (page does not exist)">Chialisp</a> </th></tr> </tbody></table> <div class="mw-heading mw-heading2"><h2 id="Distinguishing_features">Distinguishing features</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=5" title="Edit section: Distinguishing features">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Lisp_(programming_language)" title="Lisp (programming language)">Lisp (programming language)</a></div> Scheme is primarily a <a href="/wiki/Functional_programming" title="Functional programming">functional programming</a> language. It shares many characteristics with other members of the Lisp programming language family. Scheme's very simple syntax is based on <a href="/wiki/S-expression" title="S-expression">s-expressions</a>, parenthesized lists in which a prefix operator is followed by its arguments. Scheme programs thus consist of sequences of nested lists. Lists are also the main data structure in Scheme, leading to a close equivalence between source code and data formats (<a href="/wiki/Homoiconicity" title="Homoiconicity">homoiconicity</a>). Scheme programs can easily create and evaluate pieces of Scheme code dynamically. The reliance on lists as data structures is shared by all Lisp dialects. Scheme inherits a rich set of <a href="/wiki/List_(computing)" class="mw-redirect" title="List (computing)">list-processing</a> primitives such as <a href="/wiki/Cons" title="Cons"><code>cons</code></a>, <a href="/wiki/CAR_and_CDR" title="CAR and CDR"><code>car</code> and <code>cdr</code></a> from its Lisp progenitors. Scheme uses strictly but <a href="/wiki/Type_system" title="Type system">dynamically typed variables</a> and supports <a href="/wiki/First-class_function" title="First-class function">first class procedures</a>. Thus, procedures can be assigned as values to variables or passed as arguments to procedures. This section concentrates mainly on innovative features of the language, including those features that distinguish Scheme from other Lisps. Unless stated otherwise, descriptions of features relate to the R5RS standard. In examples provided in this section, the notation "===> result" is used to indicate the result of evaluating the expression on the immediately preceding line. This is the same convention used in R5RS. <div class="mw-heading mw-heading3"><h3 id="Minimalism">Minimalism</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=6" title="Edit section: Minimalism">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Minimalism_(computing)" title="Minimalism (computing)">Minimalism (computing)</a></div> Scheme is a very simple language, much easier to implement than many other languages of comparable <a href="/wiki/Expressive_power_(computer_science)" title="Expressive power (computer science)">expressive power</a>.<a href="#cite_note-easy_to_implement_scheme48-17">[17]</a> This ease is attributable to the use of <a href="/wiki/Lambda_calculus" title="Lambda calculus">lambda calculus</a> to derive much of the syntax of the language from more primitive forms. For instance of the 23 s-expression-based syntactic constructs defined in the R5RS Scheme standard, 14 are classed as derived or library forms, which can be written as macros involving more fundamental forms, principally lambda. As R5RS (§3.1) says: "The most fundamental of the variable binding constructs is the lambda expression, because all other variable binding constructs can be explained in terms of lambda expressions."<a href="#cite_note-r5rs-4">[4]</a> <dl><dd>Fundamental forms: define, lambda, quote, if, define-syntax, let-syntax, letrec-syntax, syntax-rules, set!</dd> <dd>Derived forms: do, let, let*, letrec, cond, case, and, or, begin, named let, delay, unquote, unquote-splicing, quasiquote</dd></dl> Example: a macro to implement <code>let</code> as an expression using <code>lambda</code> to perform the variable bindings. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(define-syntax let (syntax-rules () ((let ((var expr) ...) body ...) ((lambda (var ...) body ...) expr ...)))) </pre></div> Thus using <code>let</code> as defined above a Scheme implementation would rewrite "<code>(let ((a 1)(b 2)) (+ b a))</code>" as "<code>((lambda (a b) (+ b a)) 1 2)</code>", which reduces implementation's task to that of coding procedure instantiations. In 1998, Sussman and Steele remarked that the minimalism of Scheme was not a conscious design goal, but rather the unintended outcome of the design process. "We were actually trying to build something complicated and discovered, serendipitously, that we had accidentally designed something that met all our goals but was much simpler than we had intended....we realized that the lambda calculus—a small, simple formalism—could serve as the core of a powerful and expressive programming language."<a href="#cite_note-revisited-7">[7]</a> <div class="mw-heading mw-heading3"><h3 id="Lexical_scope">Lexical scope</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=7" title="Edit section: Lexical scope">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Scope_(programming)" class="mw-redirect" title="Scope (programming)">Scope (programming)</a></div> Like most modern programming languages and unlike earlier Lisps such as <a href="/wiki/Maclisp" title="Maclisp">Maclisp</a>, Scheme is lexically scoped: all possible variable bindings in a program unit can be analyzed by reading the text of the program unit without consideration of the contexts in which it may be called. This contrasts with dynamic scoping which was characteristic of early Lisp dialects, because of the processing costs associated with the primitive textual substitution methods used to implement lexical scoping algorithms in compilers and interpreters of the day. In those Lisps, it was perfectly possible for a reference to a <a href="/wiki/Free_variable" class="mw-redirect" title="Free variable">free variable</a> inside a procedure to refer to quite distinct bindings external to the procedure, depending on the context of the call. The impetus to incorporate lexical scoping, which was an unusual scoping model in the early 1970s, into their new version of Lisp, came from Sussman's studies of <a href="/wiki/ALGOL" title="ALGOL">ALGOL</a>. He suggested that <a href="/wiki/Block_(programming)" title="Block (programming)">ALGOL-like lexical scoping mechanisms</a> would help to realize their initial goal of implementing <a href="/wiki/Carl_Hewitt#Actor_model" title="Carl Hewitt">Hewitt's Actor model</a> in Lisp.<a href="#cite_note-revisited-7">[7]</a> The key insights on how to introduce lexical scoping into a Lisp dialect were popularized in Sussman and Steele's 1975 Lambda Paper, "Scheme: An Interpreter for Extended Lambda Calculus",<a href="#cite_note-lambda_paper_1-18">[18]</a> where they adopted the concept of the <a href="/wiki/Closure_(computer_science)" class="mw-redirect" title="Closure (computer science)">lexical closure</a> (on page 21), which had been described in an <a href="/wiki/AI_Memo" title="AI Memo">AI Memo</a> in 1970 by <a href="/wiki/Joel_Moses" title="Joel Moses">Joel Moses</a>, who attributed the idea to <a href="/wiki/Peter_J._Landin" class="mw-redirect" title="Peter J. Landin">Peter J. Landin</a>.<a href="#cite_note-Moses-19">[19]</a> <div class="mw-heading mw-heading3"><h3 id="Lambda_calculus">Lambda calculus</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=8" title="Edit section: Lambda calculus">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Lambda_calculus" title="Lambda calculus">Lambda calculus</a></div> <a href="/wiki/Alonzo_Church" title="Alonzo Church">Alonzo Church</a>'s mathematical notation, the lambda calculus, has inspired Lisp's use of "lambda" as a keyword for introducing a procedure, as well as influencing the development of <a href="/wiki/Functional_programming" title="Functional programming">functional programming</a> techniques involving the use of <a href="/wiki/Higher-order_function" title="Higher-order function">higher-order functions</a> in Lisp. But early Lisps were not suitable expressions of the lambda calculus because of their treatment of <a href="/wiki/Free_variables_and_bound_variables" title="Free variables and bound variables">free variables</a>.<a href="#cite_note-revisited-7">[7]</a> A formal lambda system has axioms and a complete calculation rule. It is helpful for the analysis using mathematical logic and tools. In this system, calculation can be seen as a directional deduction. The syntax of lambda calculus follows the recursive expressions from x, y, z, ...,parentheses, spaces, the period and the symbol λ.<a href="#cite_note-20">[20]</a> The function of lambda calculation includes: First, serve as a starting point of powerful mathematical logic. Second, it can reduce the requirement of programmers to consider the implementation details, because it can be used to imitate machine evaluation. Finally, the lambda calculation created a substantial meta-theory.<a href="#cite_note-21">[21]</a> The introduction of lexical scope resolved the problem by making an equivalence between some forms of lambda notation and their practical expression in a working programming language. Sussman and Steele showed that the new language could be used to elegantly derive all the imperative and declarative semantics of other programming languages including ALGOL and <a href="/wiki/Fortran" title="Fortran">Fortran</a>, and the dynamic scope of other Lisps, by using lambda expressions not as simple procedure instantiations but as "control structures and environment modifiers".<a href="#cite_note-lambda_paper_2-22">[22]</a> They introduced <a href="/wiki/Continuation-passing_style" title="Continuation-passing style">continuation-passing style</a> along with their first description of Scheme in the first of the Lambda Papers, and in subsequent papers, they proceeded to demonstrate the raw power of this practical use of lambda calculus. <div class="mw-heading mw-heading3"><h3 id="Block_structure">Block structure</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=9" title="Edit section: Block structure">edit</a>]</div> Scheme inherits its block structure from earlier block structured languages, particularly <a href="/wiki/ALGOL" title="ALGOL">ALGOL</a>. In Scheme, blocks are implemented by three binding constructs: <a href="/wiki/Let_expression" title="Let expression"><code>let</code></a>, <code>let*</code> and <code>letrec</code>. For instance, the following construct creates a <a href="/wiki/Block_(programming)" title="Block (programming)">block</a> in which a symbol called <code>var</code> is bound to the number 10: <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(define var "goose") ;; Any reference to var here will be bound to "goose" (let ((var 10)) ;; statements go here. Any reference to var here will be bound to 10. ) ;; Any reference to var here will be bound to "goose" </pre></div> Blocks can be <a href="/wiki/Nesting_(computing)" title="Nesting (computing)">nested</a> to create arbitrarily complex block structures according to the need of the programmer. The use of block structuring to create local bindings alleviates the risk of <a href="/wiki/Naming_collision" title="Naming collision">namespace collision</a> that can otherwise occur. One variant of <code>let</code>, <code>let*</code>, permits bindings to refer to variables defined earlier in the same construct, thus: <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(let* ((var1 10) (var2 (+ var1 12))) ;; But the definition of var1 could not refer to var2 ) </pre></div> The other variant, <code>letrec</code>, is designed to enable <a href="/wiki/Mutual_recursion" title="Mutual recursion">mutually recursive</a> procedures to be bound to one another. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>;; Calculation of Hofstadter's male and female sequences as a list of pairs (define (hofstadter-male-female n) (letrec ((female (lambda (n) (if (= n 0) 1 (- n (male (female (- n 1))))))) (male (lambda (n) (if (= n 0) 0 (- n (female (male (- n 1)))))))) (let loop ((i 0)) (if (> i n) '() (cons (cons (female i) (male i)) (loop (+ i 1))))))) (hofstadter-male-female 8) ===> ((1 . 0) (1 . 0) (2 . 1) (2 . 2) (3 . 2) (3 . 3) (4 . 4) (5 . 4) (5 . 5)) </pre></div> (See <a href="/wiki/Hofstadter_sequence#Hofstadter_Female_and_Male_sequences" title="Hofstadter sequence">Hofstadter's male and female sequences</a> for the definitions used in this example.) All procedures bound in a single <code>letrec</code> may refer to one another by name, as well as to values of variables defined earlier in the same <code>letrec</code>, but they may not refer to values defined later in the same <code>letrec</code>. A variant of <code>let</code>, the "named let" form, has an identifier after the <code>let</code> keyword. This binds the let variables to the argument of a procedure whose name is the given identifier and whose body is the body of the let form. The body may be repeated as desired by calling the procedure. The named let is widely used to implement iteration. Example: a simple counter <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(let loop ((n 1)) (if (> n 10) '() (cons n (loop (+ n 1))))) ===> (1 2 3 4 5 6 7 8 9 10) </pre></div> Like any procedure in Scheme, the procedure created in the named let is a first-class object. <div class="mw-heading mw-heading3"><h3 id="Proper_tail_recursion">Proper tail recursion</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=10" title="Edit section: Proper tail recursion">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Further information: <a href="/wiki/Tail_recursion" class="mw-redirect" title="Tail recursion">Tail recursion</a></div> Scheme has an iteration construct, <code>do</code>, but it is more <a href="/wiki/Programming_idiom" title="Programming idiom">idiomatic</a> in Scheme to use <a href="/wiki/Tail_recursion" class="mw-redirect" title="Tail recursion">tail recursion</a> to express <a href="/wiki/Iteration" title="Iteration">iteration</a>. Standard-conforming Scheme implementations are required to optimize tail calls so as to support an unbounded number of active tail calls (R5RS sec. 3.5)<a href="#cite_note-r5rs-4">[4]</a>—a property the Scheme report describes as proper tail recursion—making it safe for Scheme programmers to write iterative algorithms using recursive structures, which are sometimes more intuitive. Tail recursive procedures and the named <code>let</code> form provide support for iteration using tail recursion. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>;; Building a list of squares from 0 to 9: ;; Note: loop is simply an arbitrary symbol used as a label. Any symbol will do. (define (list-of-squares n) (let loop ((i n) (res '())) (if (< i 0) res (loop (- i 1) (cons (* i i) res))))) (list-of-squares 9) ===> (0 1 4 9 16 25 36 49 64 81) </pre></div> <div class="mw-heading mw-heading3"><h3 id="First-class_continuations">First-class continuations</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=11" title="Edit section: First-class continuations">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Continuation" title="Continuation">Continuation</a></div> Continuations in Scheme are <a href="/wiki/First-class_object" class="mw-redirect" title="First-class object">first-class objects</a>. Scheme provides the procedure <code><a href="/wiki/Call-with-current-continuation" title="Call-with-current-continuation">call-with-current-continuation</a></code> (also known as <code>call/cc</code>) to capture the current continuation by packing it up as an escape procedure bound to a formal argument in a procedure provided by the programmer. (R5RS sec. 6.4)<a href="#cite_note-r5rs-4">[4]</a> First-class continuations enable the programmer to create non-local <a href="/wiki/Control_flow" title="Control flow">control constructs</a> such as <a href="/wiki/Iterator" title="Iterator">iterators</a>, <a href="/wiki/Coroutine" title="Coroutine">coroutines</a>, and <a href="/wiki/Backtracking" title="Backtracking">backtracking</a>. Continuations can be used to emulate the behavior of <a href="/wiki/Return_statement" title="Return statement">return statements</a> in imperative programming languages. The following function <code>find-first</code>, given function <code>func</code> and list <code>lst</code>, returns the first element <code>x</code> in <code>lst</code> such that <code>(func x)</code> returns true. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(define (find-first func lst) (call-with-current-continuation (lambda (return-immediately) (for-each (lambda (x) (if (func x) (return-immediately x))) lst) #f))) (find-first integer? '(1/2 3/4 5.6 7 8/9 10 11)) ===> 7 (find-first zero? '(1 2 3 4)) ===> #f </pre></div> The following example, a traditional programmer's puzzle, shows that Scheme can handle continuations as first-class objects, binding them to variables and passing them as arguments to procedures. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(let* ((yin ((lambda (cc) (display "@") cc) (call-with-current-continuation (lambda (c) c)))) (yang ((lambda (cc) (display "*") cc) (call-with-current-continuation (lambda (c) c))))) (yin yang)) </pre></div> When executed this code displays a counting sequence: <code>@*@**@***@****@*****@******@*******@********...</code> <div class="mw-heading mw-heading3"><h3 id="Shared_namespace_for_procedures_and_variables">Shared namespace for procedures and variables</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=12" title="Edit section: Shared namespace for procedures and variables">edit</a>]</div> In contrast to Common Lisp, all data and procedures in Scheme share a common namespace, whereas in Common Lisp <a href="/wiki/Common_Lisp#The_function_namespace" title="Common Lisp">functions and data have separate namespaces</a> making it possible for a function and a variable to have the same name, and requiring special notation for referring to a function as a value. This is sometimes known as the "<a href="/wiki/Lisp-1_vs._Lisp-2" class="mw-redirect" title="Lisp-1 vs. Lisp-2">Lisp-1 vs. Lisp-2</a>" distinction, referring to the unified namespace of Scheme and the separate namespaces of Common Lisp.<a href="#cite_note-23">[23]</a> In Scheme, the same primitives that are used to manipulate and bind data can be used to bind procedures. There is no equivalent of Common Lisp's <code>defun</code> and <code>#'</code> primitives. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>;; Variable bound to a number: (define f 10) f ===> 10 ;; Mutation (altering the bound value) (set! f (+ f f 6)) f ===> 26 ;; Assigning a procedure to the same variable: (set! f (lambda (n) (+ n 12))) (f 6) ===> 18 ;; Assigning the result of an expression to the same variable: (set! f (f 1)) f ===> 13 ;; functional programming: (apply + '(1 2 3 4 5 6)) ===> 21 (set! f (lambda (n) (+ n 100))) (map f '(1 2 3)) ===> (101 102 103) </pre></div> <div class="mw-heading mw-heading2"><h2 id="Implementation_standards">Implementation standards</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=13" title="Edit section: Implementation standards">edit</a>]</div> This subsection documents design decisions that have been taken over the years which have given Scheme a particular character, but are not the direct outcomes of the original design. <div class="mw-heading mw-heading3"><h3 id="Numerical_tower">Numerical tower</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=14" title="Edit section: Numerical tower">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Numerical_tower" title="Numerical tower">Numerical tower</a></div> Scheme specifies a comparatively full set of numerical datatypes including <a href="/wiki/Complex_number" title="Complex number">complex</a> and <a href="/wiki/Rational_number" title="Rational number">rational</a> types, which is known in Scheme as the numerical tower (R5RS sec. 6.2<a href="#cite_note-r5rs-4">[4]</a>). The standard treats these as abstractions, and does not commit the implementor to any particular internal representations. Numbers may have the quality of exactness. An exact number can only be produced by a sequence of exact operations involving other exact numbers—inexactness is thus contagious. The standard specifies that any two implementations must produce equivalent results for all operations resulting in exact numbers. The R5RS standard specifies procedures <code>exact->inexact</code> and <code>inexact->exact</code> which can be used to change the exactness of a number. <code>inexact->exact</code> produces "the exact number that is numerically closest to the argument". <code>exact->inexact</code> produces "the inexact number that is numerically closest to the argument". The R6RS standard omits these procedures from the main report, but specifies them as R5RS compatibility procedures in the standard library (rnrs r5rs (6)). In the R5RS standard, Scheme implementations are not required to implement the whole numerical tower, but they must implement "a coherent subset consistent with both the purposes of the implementation and the spirit of the Scheme language" (R5RS sec. 6.2.3).<a href="#cite_note-r5rs-4">[4]</a> The new R6RS standard does require implementation of the whole tower, and "exact integer objects and exact rational number objects of practically unlimited size and precision, and to implement certain procedures...so they always return exact results when given exact arguments" (R6RS sec. 3.4, sec. 11.7.1).<a href="#cite_note-r6rs-6">[6]</a> Example 1: exact arithmetic in an implementation that supports exact rational complex numbers. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>;; Sum of three rational real numbers and two rational complex numbers (define x (+ 1/3 1/4 -1/5 -1/3i 405/50+2/3i)) x ===> 509/60+1/3i ;; Check for exactness. (exact? x) ===> #t </pre></div> Example 2: Same arithmetic in an implementation that supports neither exact rational numbers nor complex numbers but does accept real numbers in rational notation. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>;; Sum of four rational real numbers (define xr (+ 1/3 1/4 -1/5 405/50)) ;; Sum of two rational real numbers (define xi (+ -1/3 2/3)) xr ===> 8.48333333333333 xi ===> 0.333333333333333 ;; Check for exactness. (exact? xr) ===> #f (exact? xi) ===> #f </pre></div> Both implementations conform to the R5RS standard but the second does not conform to R6RS because it does not implement the full numerical tower. <div class="mw-heading mw-heading3"><h3 id="Delayed_evaluation">Delayed evaluation</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=15" title="Edit section: Delayed evaluation">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Lazy_evaluation" title="Lazy evaluation">Lazy evaluation</a></div> Scheme supports delayed evaluation through the <code>delay</code> form and the procedure <code>force</code>. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(define a 10) (define eval-aplus2 (delay (+ a 2))) (set! a 20) (force eval-aplus2) ===> 22 (define eval-aplus50 (delay (+ a 50))) (let ((a 8)) (force eval-aplus50)) ===> 70 (set! a 100) (force eval-aplus2) ===> 22 </pre></div> The lexical context of the original definition of the promise is preserved, and its value is also preserved after the first use of <code>force</code>. The promise is only ever evaluated once. These primitives, which produce or handle values known as <a href="/wiki/Futures_and_promises" title="Futures and promises">promises</a>, can be used to implement advanced <a href="/wiki/Lazy_evaluation" title="Lazy evaluation">lazy evaluation</a> constructs such as <a href="/wiki/Stream_(computing)" title="Stream (computing)">streams</a>.<a href="#cite_note-srfi-41-24">[24]</a> In the R6RS standard, these are no longer primitives, but instead, are provided as part of the R5RS compatibility library (rnrs r5rs (6)). In R5RS, a suggested implementation of <code>delay</code> and <code>force</code> is given, implementing the promise as a procedure with no arguments (a <a href="/wiki/Thunk" title="Thunk">thunk</a>) and using <a href="/wiki/Memoization" title="Memoization">memoization</a> to ensure that it is only ever evaluated once, irrespective of the number of times <code>force</code> is called (R5RS sec. 6.4).<a href="#cite_note-r5rs-4">[4]</a> SRFI 41 enables the expression of both finite and infinite sequences with extraordinary economy. For example, this is a definition of the <a href="/wiki/Fibonacci_sequence" title="Fibonacci sequence">Fibonacci sequence</a> using the functions defined in SRFI 41:<a href="#cite_note-srfi-41-24">[24]</a> <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>;; Define the Fibonacci sequence: (define fibs (stream-cons 0 (stream-cons 1 (stream-map + fibs (stream-cdr fibs))))) ;; Compute the hundredth number in the sequence: (stream-ref fibs 99) ===> 218922995834555169026 </pre></div> <div class="mw-heading mw-heading3"><h3 id="Order_of_evaluation_of_procedure_arguments">Order of evaluation of procedure arguments</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=16" title="Edit section: Order of evaluation of procedure arguments">edit</a>]</div> Most Lisps specify an order of evaluation for procedure arguments. Scheme does not. Order of evaluation—including the order in which the expression in the operator position is evaluated—may be chosen by an implementation on a call-by-call basis, and the only constraint is that "the effect of any concurrent evaluation of the operator and operand expressions is constrained to be consistent with some sequential order of evaluation." (R5RS sec. 4.1.3)<a href="#cite_note-r5rs-4">[4]</a> <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(let ((ev (lambda(n) (display "Evaluating ") (display (if (procedure? n) "procedure" n)) (newline) n))) ((ev +) (ev 1) (ev 2))) ===> 3 </pre></div> <div class="mw-highlight mw-highlight-lang-output mw-content-ltr" dir="ltr"><pre>Evaluating 1 Evaluating 2 Evaluating procedure </pre></div> ev is a procedure that describes the argument passed to it, then returns the value of the argument. In contrast with other Lisps, the appearance of an expression in the operator position (the first item) of a Scheme expression is quite legal, as long as the result of the expression in the operator position is a procedure. In calling the procedure "<style data-mw-deduplicate="TemplateStyles:r886049734">.mw-parser-output .monospaced{font-family:monospace,monospace}</style>+" to add 1 and 2, the expressions <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">(ev +), (ev 1) and <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">(ev 2) may be evaluated in any order, as long as the effect is not as if they were evaluated in parallel. Thus the following three lines may be displayed in any order by standard Scheme when the above example code is executed, although the text of one line may not be interleaved with another because that would violate the sequential evaluation constraint. <div class="mw-heading mw-heading3"><h3 id="Hygienic_macros">Hygienic macros</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=17" title="Edit section: Hygienic macros">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Hygienic_macro" title="Hygienic macro">Hygienic macro</a></div> In the R5RS standard and also in later reports, the syntax of Scheme can easily be extended via the macro system. The R5RS standard introduced a powerful hygienic macro system that allows the programmer to add new syntactic constructs to the language using a simple <a href="/wiki/Pattern_matching" title="Pattern matching">pattern matching</a> sublanguage (R5RS sec 4.3).<a href="#cite_note-r5rs-4">[4]</a> Prior to this, the hygienic macro system had been relegated to an appendix of the R4RS standard, as a "high level" system alongside a "low level" macro system, both of which were treated as extensions to Scheme rather than an essential part of the language.<a href="#cite_note-r4rs-25">[25]</a> Implementations of the hygienic macro system, also called <code>syntax-rules</code>, are required to respect the lexical scoping of the rest of the language. This is assured by special naming and scoping rules for macro expansion and avoids common programming errors that can occur in the macro systems of other programming languages. R6RS specifies a more sophisticated transformation system, <code>syntax-case</code>, which has been available as a language extension to R5RS Scheme for some time. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>;; Define a macro to implement a variant of "if" with a multi-expression ;; true branch and no false branch. (define-syntax when (syntax-rules () ((when pred exp exps ...) (if pred (begin exp exps ...))))) </pre></div> Invocations of macros and procedures bear a close resemblance—both are s-expressions—but they are treated differently. When the compiler encounters an s-expression in the program, it first checks to see if the symbol is defined as a syntactic keyword within the current lexical scope. If so, it then attempts to expand the macro, treating the items in the tail of the s-expression as arguments without compiling code to evaluate them, and this process is repeated recursively until no macro invocations remain. If it is not a syntactic keyword, the compiler compiles code to evaluate the arguments in the tail of the s-expression and then to evaluate the variable represented by the symbol at the head of the s-expression and call it as a procedure with the evaluated tail expressions passed as arguments to it. Most Scheme implementations also provide additional macro systems. Among popular ones are <a href="/wiki/Hygienic_macro#syntactic_closures" title="Hygienic macro">syntactic closures</a>, <a href="/wiki/Hygienic_macro#explicit_renaming" title="Hygienic macro">explicit renaming macros</a> and <code>define-macro</code>, a non-hygienic macro system similar to <code>defmacro</code> system provided in <a href="/wiki/Common_Lisp" title="Common Lisp">Common Lisp</a>. The inability to specify whether or not a macro is hygienic is one of the shortcomings of the macro system. Alternative models for expansion such as scope sets provide a potential solution.<a href="#cite_note-26">[26]</a> <div class="mw-heading mw-heading3"><h3 id="Environments_and_eval">Environments and eval</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=18" title="Edit section: Environments and eval">edit</a>]</div> Prior to R5RS, Scheme had no standard equivalent of the <code>eval</code> procedure which is ubiquitous in other Lisps, although the first Lambda Paper had described <code>evaluate</code> as "similar to the LISP function EVAL"<a href="#cite_note-lambda_paper_1-18">[18]</a> and the first Revised Report in 1978 replaced this with <code>enclose</code>, which took two arguments. The second, third and fourth revised reports omitted any equivalent of <code>eval</code>. The reason for this confusion is that in Scheme with its lexical scoping the result of evaluating an expression depends on where it is evaluated. For instance, it is not clear whether the result of evaluating the following expression should be 5 or 6:<a href="#cite_note-rees_1992-27">[27]</a> <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(let ((name '+)) (let ((+ *)) (evaluate (list name 2 3)))) </pre></div> If it is evaluated in the outer environment, where <code>name</code> is defined, the result is the sum of the operands. If it is evaluated in the inner environment, where the symbol "+" has been bound to the value of the procedure "*", the result is the product of the two operands. R5RS resolves this confusion by specifying three procedures that return environments and providing a procedure <code>eval</code> that takes an s-expression and an environment and evaluates the expression in the environment provided. (R5RS sec. 6.5)<a href="#cite_note-r5rs-4">[4]</a> R6RS extends this by providing a procedure called <code>environment</code> by which the programmer can specify exactly which objects to import into the evaluation environment. With modern scheme (usually compatible with R5RS) to evaluate this expression, one needs to define a function <code>evaluate</code> which can look like this: <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(define (evaluate expr) (eval expr (interaction-environment))) </pre></div> <code>interaction-environment</code> is the interpreter's global environment. <div class="mw-heading mw-heading3"><h3 id="Treatment_of_non-Boolean_values_in_Boolean_expressions">Treatment of non-Boolean values in Boolean expressions</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=19" title="Edit section: Treatment of non-Boolean values in Boolean expressions">edit</a>]</div> In most dialects of Lisp including Common Lisp, by convention the value <code>NIL</code> evaluates to the value false in a Boolean expression. In Scheme, since the IEEE standard in 1991,<a href="#cite_note-ieee1178-3">[3]</a> all values except <code>#f</code>, including <code>NIL</code>'s equivalent in Scheme which is written as <code>'()</code>, evaluate to the value true in a Boolean expression. (R5RS sec. 6.3.1)<a href="#cite_note-r5rs-4">[4]</a> Where the constant representing the Boolean value of true is <code>T</code> in most Lisps, in Scheme it is <code>#t</code>. <div class="mw-heading mw-heading3"><h3 id="Disjointness_of_primitive_datatypes">Disjointness of primitive datatypes</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=20" title="Edit section: Disjointness of primitive datatypes">edit</a>]</div> In Scheme the primitive datatypes are disjoint. Only one of the following predicates can be true of any Scheme object: <code>boolean?</code>, <code>pair?</code>, <code>symbol?</code>, <code>number?</code>, <code>char?</code>, <code>string?</code>, <code>vector?</code>, <code>port?</code>, <code>procedure?</code>. (R5RS sec 3.2)<a href="#cite_note-r5rs-4">[4]</a> Within the numerical datatype, by contrast, the numerical values overlap. For example, an integer value satisfies all of the <code>integer?</code>, <code>rational?</code>, <code>real?</code>, <code>complex?</code> and <code>number?</code> predicates at the same time. (R5RS sec 6.2)<a href="#cite_note-r5rs-4">[4]</a> <div class="mw-heading mw-heading3"><h3 id="Equivalence_predicates">Equivalence predicates</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=21" title="Edit section: Equivalence predicates">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Relational_operator" title="Relational operator">relational operator</a></div> Scheme has three different types of equivalence between arbitrary objects denoted by three different equivalence predicates, relational operators for testing equality, <code>eq?</code>, <code>eqv?</code> and <code>equal?</code>: <ul><li><code>eq?</code> evaluates to <code>#f</code> unless its parameters represent the same data object in memory;</li> <li><code>eqv?</code> is generally the same as <code>eq?</code> but treats primitive objects (e.g. characters and numbers) specially so that numbers that represent the same value are <code>eqv?</code> even if they do not refer to the same object;</li> <li><code>equal?</code> compares data structures such as lists, vectors and strings to determine if they have congruent structure and <code>eqv?</code> contents.(R5RS sec. 6.1)<a href="#cite_note-r5rs-4">[4]</a></li></ul> Type dependent equivalence operations also exist in Scheme: <code>string=?</code> and <code>string-ci=?</code> compare two strings (the latter performs a case-independent comparison); <code>char=?</code> and <code>char-ci=?</code> compare characters; <code>=</code> compares numbers.<a href="#cite_note-r5rs-4">[4]</a> <div class="mw-heading mw-heading3"><h3 id="Comments">Comments</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=22" title="Edit section: Comments">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">See also: <a href="/wiki/Comment_(computer_programming)" title="Comment (computer programming)">Comment (computer programming)</a></div> Up to the R5RS standard, the standard comment in Scheme was a semicolon, which makes the rest of the line invisible to Scheme. Numerous implementations have supported alternative conventions permitting comments to extend for more than a single line, and the R6RS standard permits two of them: an entire <a href="/wiki/S-expression" title="S-expression">s-expression</a> may be turned into a comment (or "commented out") by preceding it with <code>#;</code> (introduced in SRFI 62<a href="#cite_note-28">[28]</a>) and a multiline comment or "block comment" may be produced by surrounding text with <code>#|</code> and <code>|#</code>. <div class="mw-heading mw-heading3"><h3 id="Input/output">Input/output</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=23" title="Edit section: Input/output">edit</a>]</div> Scheme's input and output is based on the port datatype. (R5RS sec 6.6)<a href="#cite_note-r5rs-4">[4]</a> R5RS defines two default ports, accessible with the procedures <code>current-input-port</code> and <code>current-output-port</code>, which correspond to the Unix notions of <a href="/wiki/Standard_streams" title="Standard streams">standard input and standard output</a>. Most implementations also provide <code>current-error-port</code>. <a href="/wiki/Redirection_(computing)" title="Redirection (computing)">Redirection</a> of input and standard output is supported in the standard, by standard procedures such as <code>with-input-from-file</code> and <code>with-output-to-file</code>. Most implementations provide string ports with similar redirection capabilities, enabling many normal input-output operations to be performed on string buffers instead of files, using procedures described in SRFI 6.<a href="#cite_note-srfi-6-29">[29]</a> The R6RS standard specifies much more sophisticated and capable port procedures and many new types of port. The following examples are written in strict R5RS Scheme. Example 1: With output defaulting to (current-output-port): <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(let ((hello0 (lambda() (display "Hello world") (newline)))) (hello0)) </pre></div> Example 2: As 1, but using optional port argument to output procedures <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(let ((hello1 (lambda (p) (display "Hello world" p) (newline p)))) (hello1 (current-output-port))) </pre></div> Example 3: As 1, but output is redirected to a newly created file <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>;; NB: with-output-to-file is an optional procedure in R5RS (let ((hello0 (lambda () (display "Hello world") (newline)))) (with-output-to-file "helloworldoutputfile" hello0)) </pre></div> Example 4: As 2, but with explicit file open and port close to send output to file <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(let ((hello1 (lambda (p) (display "Hello world" p) (newline p))) (output-port (open-output-file "helloworldoutputfile"))) (hello1 output-port) (close-output-port output-port)) </pre></div> Example 5: As 2, but with using call-with-output-file to send output to a file. <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(let ((hello1 (lambda (p) (display "Hello world" p) (newline p)))) (call-with-output-file "helloworldoutputfile" hello1)) </pre></div> Similar procedures are provided for input. R5RS Scheme provides the predicates <code>input-port?</code> and <code>output-port?</code>. For character input and output, <code>write-char</code>, <code>read-char</code>, <code>peek-char</code> and <code>char-ready?</code> are provided. For writing and reading Scheme expressions, Scheme provides <code>read</code> and <code>write</code>. On a read operation, the result returned is the end-of-file object if the input port has reached the end of the file, and this can be tested using the predicate <code>eof-object?</code>. With the standard, SRFI 28 also defines a basic formatting procedure resembling Common Lisp's <code>format</code> function, after which it is named.<a href="#cite_note-srfi-28-30">[30]</a> <div class="mw-heading mw-heading3"><h3 id="Redefinition_of_standard_procedures">Redefinition of standard procedures</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=24" title="Edit section: Redefinition of standard procedures">edit</a>]</div> In Scheme, procedures are bound to variables. At R5RS the language standard formally mandated that programs may change the variable bindings of built-in procedures, effectively redefining them. (R5RS "Language changes")<a href="#cite_note-r5rs-4">[4]</a> For example, <code>+</code> can be extended to accept strings as well as numbers by redefining it: <div class="mw-highlight mw-highlight-lang-scheme mw-content-ltr" dir="ltr"><pre>(set! + (let ((original+ +)) (lambda args (apply (if (or (null? args) (string? (car args))) string-append original+) args)))) (+ 1 2 3) ===> 6 (+ "1" "2" "3") ===> "123" </pre></div> In R6RS every binding, including the standard ones, belongs to some library, and all exported bindings are immutable. (R6RS sec 7.1)<a href="#cite_note-r6rs-6">[6]</a> Because of this, redefinition of standard procedures by mutation is forbidden. Instead, it is possible to import a different procedure under the name of a standard one, which in effect is similar to redefinition. <div class="mw-heading mw-heading3"><h3 id="Nomenclature_and_naming_conventions">Nomenclature and naming conventions</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=25" title="Edit section: Nomenclature and naming conventions">edit</a>]</div> In Standard Scheme, procedures that convert from one datatype to another contain the character string "->" in their name, predicates end with a "?", and procedures that change the value of already-allocated data end with a "!". These conventions are often followed by Scheme programmers. In formal contexts such as Scheme standards, the word "procedure" is used in preference to "function" to refer to a lambda expression or primitive procedure. In normal usage, the words "procedure" and "function" are used interchangeably. Procedure application is sometimes referred to formally as combination. As in other Lisps, the term "<a href="/wiki/Thunk" title="Thunk">thunk</a>" is used in Scheme to refer to a procedure with no arguments. The term "proper tail recursion" refers to the property of all Scheme implementations, that they perform tail-call optimization so as to support an indefinite number of active <a href="/wiki/Tail_call" title="Tail call">tail calls</a>. The form of the titles of the standards documents since R3RS, "Revisedn Report on the Algorithmic Language Scheme", is a reference to the title of the <a href="/wiki/ALGOL" title="ALGOL">ALGOL 60</a> standard document, "Revised Report on the Algorithmic Language Algol 60," The Summary page of R3RS is closely modeled on the Summary page of the ALGOL 60 Report.<a href="#cite_note-algol_report-31">[31]</a><a href="#cite_note-r3rs-32">[32]</a> <div class="mw-heading mw-heading2"><h2 id="Review_of_standard_forms_and_procedures">Review of standard forms and procedures</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=26" title="Edit section: Review of standard forms and procedures">edit</a>]</div> The language is formally defined in the standards R5RS (1998)<a href="#cite_note-r5rs-4">[4]</a> and R6RS (2007).<a href="#cite_note-r6rs-6">[6]</a> They describe standard "forms": keywords and accompanying syntax, which provide the control structure of the language, and standard procedures which perform common tasks. <div class="mw-heading mw-heading3"><h3 id="Standard_forms">Standard forms</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=27" title="Edit section: Standard forms">edit</a>]</div> This table describes the standard forms in Scheme. Some forms appear in more than one row because they cannot easily be classified into a single function in the language. Forms marked "L" in this table are classed as derived "library" forms in the standard and are often implemented as macros using more fundamental forms in practice, making the task of implementation much easier than in other languages. <table class="wikitable"> <caption>Standard forms in the language R5RS Scheme </caption> <tbody><tr> <th>Purpose</th> <th>Forms </th></tr> <tr> <td>Definition</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">define </td></tr> <tr> <td>Binding constructs</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">lambda, do (L), let (L), let* (L), letrec (L) </td></tr> <tr> <td>Conditional evaluation</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">if, cond (L), case (L), and (L), or (L) </td></tr> <tr> <td>Sequential evaluation</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">begin (*) </td></tr> <tr> <td>Iteration</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">lambda, do (L), named let (L) </td></tr> <tr> <td>Syntactic extension</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">define-syntax, let-syntax, letrec-syntax, syntax-rules (R5RS), syntax-case (R6RS) </td></tr> <tr> <td>Quoting</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">quote('), unquote(,), quasiquote(`), unquote-splicing(,@) </td></tr> <tr> <td>Assignment</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">set! </td></tr> <tr> <td>Delayed evaluation</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">delay (L) </td></tr></tbody></table> While <code>begin</code> is defined as a library syntax in R5RS, the expander must know about it to achieve the splicing function. In R6RS it is no longer a library syntax. <div class="mw-heading mw-heading3"><h3 id="Standard_procedures">Standard procedures</h3>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=28" title="Edit section: Standard procedures">edit</a>]</div> The following two tables describe the standard procedures in R5RS Scheme. R6RS is far more extensive and a summary of this type would not be practical. Some procedures appear in more than one row because they cannot easily be classified into a single function in the language. <table class="wikitable"> <caption>Standard procedures in the language R5RS Scheme </caption> <tbody><tr> <th>Purpose</th> <th>Procedures </th></tr> <tr> <td>Construction</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">vector, make-vector, make-string, list </td></tr> <tr> <td>Equivalence predicates</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">eq?, eqv?, equal?, string=?, string-ci=?, char=?, char-ci=? </td></tr> <tr> <td><a href="/wiki/Type_conversion" title="Type conversion">Type conversion</a></td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">vector->list, list->vector, number->string, string->number, symbol->string, string->symbol, char->integer, integer->char, string->list, list->string </td></tr> <tr> <td>Numbers</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">See separate table </td></tr> <tr> <td>Strings</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">string?, make-string, string, string-length, string-ref, string-set!, string=?, string-ci=?, string<? string-ci<?, string<=? string-ci<=?, string>? string-ci>?, string>=? string-ci>=?, substring, string-append, string->list, list->string, string-copy, string-fill! </td></tr> <tr> <td>Characters</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">char?, char=?, char-ci=?, char<? char-ci<?, char<=? char-ci<=?, char>? char-ci>?, char>=? char-ci>=?, char-alphabetic?, char-numeric?, char-whitespace?, char-upper-case?, char-lower-case?, char->integer, integer->char, char-upcase, char-downcase </td></tr> <tr> <td>Vectors</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">make-vector, vector, vector?, vector-length, vector-ref, vector-set!, vector->list, list->vector, vector-fill! </td></tr> <tr> <td>Symbols</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">symbol->string, string->symbol, symbol? </td></tr> <tr> <td>Pairs and lists</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">pair?, cons, car, cdr, set-car!, set-cdr!, null?, list?, list, length, append, reverse, list-tail, list-ref, memq. memv. member, assq, assv, assoc, list->vector, vector->list, list->string, string->list </td></tr> <tr> <td>Identity predicates</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">boolean?, pair?, symbol?, number?, char?, string?, vector?, port?, procedure? </td></tr> <tr> <td>Continuations</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">call-with-current-continuation (call/cc), values, call-with-values, dynamic-wind </td></tr> <tr> <td>Environments</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">eval, scheme-report-environment, null-environment, interaction-environment (optional) </td></tr> <tr> <td>Input/output</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">display, newline, read, write, read-char, write-char, peek-char, char-ready?, eof-object? open-input-file, open-output-file, close-input-port, close-output-port, input-port?, output-port?, current-input-port, current-output-port, call-with-input-file, call-with-output-file, with-input-from-file(optional), with-output-to-file(optional) </td></tr> <tr> <td>System interface</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">load (optional), transcript-on (optional), transcript-off (optional) </td></tr> <tr> <td>Delayed evaluation</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">force </td></tr> <tr> <td>Functional programming</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">procedure?, apply, map, for-each </td></tr> <tr> <td>Booleans</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">boolean? not </td></tr></tbody></table> String and character procedures that contain "-ci" in their names perform case-independent comparisons between their arguments: upper case and lower case versions of the same character are taken to be equal. <table class="wikitable"> <caption>Standard numeric procedures in the language R5RS Scheme </caption> <tbody><tr> <th>Purpose</th> <th>Procedures </th></tr> <tr> <td>Basic arithmetic operators</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">+, -, *, /, abs, quotient, remainder, modulo, gcd, lcm, expt, sqrt </td></tr> <tr> <td>Rational numbers</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">numerator, denominator, rational?, rationalize </td></tr> <tr> <td>Approximation</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">floor, ceiling, truncate, round </td></tr> <tr> <td>Exactness</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">inexact->exact, exact->inexact, exact?, inexact? </td></tr> <tr> <td>Inequalities</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734"><, <= , >, >=, = </td></tr> <tr> <td>Miscellaneous predicates</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">zero?, negative?, positive? odd? even? </td></tr> <tr> <td>Maximum and minimum</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">max, min </td></tr> <tr> <td>Trigonometry</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">sin, cos, tan, asin, acos, atan </td></tr> <tr> <td>Exponentials</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">exp, log </td></tr> <tr> <td>Complex numbers</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">make-rectangular, make-polar, real-part, imag-part, magnitude, angle, complex? </td></tr> <tr> <td>Input-output</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">number->string, string->number </td></tr> <tr> <td>Type predicates</td> <td><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r886049734">integer?, rational?, real?, complex?, number? </td></tr></tbody></table> Implementations of - and / that take more than two arguments are defined but left optional at R5RS. <div class="mw-heading mw-heading2"><h2 id="Scheme_Requests_for_Implementation">Scheme Requests for Implementation</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=29" title="Edit section: Scheme Requests for Implementation">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main article: <a href="/wiki/Scheme_Requests_for_Implementation" title="Scheme Requests for Implementation">Scheme Requests for Implementation</a></div> Because of Scheme's minimalism, many common procedures and syntactic forms are not defined by the standard. In order to keep the core language small but facilitate standardization of extensions, the Scheme community has a "Scheme Request for Implementation" (SRFI) process by which extension libraries are defined through careful discussion of extension proposals. This promotes code portability. Many of the SRFIs are supported by all or most Scheme implementations. SRFIs with fairly wide support in different implementations include:<a href="#cite_note-srfi_support-33">[33]</a> <ul><li>0: feature-based conditional expansion construct</li> <li>1: list library</li> <li>4: homogeneous numeric vector datatypes</li> <li>6: basic string ports</li> <li>8: receive, binding to multiple values</li> <li>9: defining record types</li> <li>13: string library</li> <li>14: character-set library</li> <li>16: syntax for procedures of variable <a href="/wiki/Arity" title="Arity">arity</a></li> <li>17: generalized set!</li> <li>18: Multithreading support</li> <li>19: time data types and procedures</li> <li>25: multi-dimensional array primitives</li> <li>26: notation for specializing parameters without <a href="/wiki/Currying" title="Currying">currying</a></li> <li>27: sources of random bits</li> <li>28: basic format strings</li> <li>29: <a href="/wiki/Internationalization_and_localization" title="Internationalization and localization">localization</a></li> <li>30: nested multi-line comments</li> <li>31: a special form for recursive evaluation</li> <li>37: args-fold: a program argument processor</li> <li>39: parameter objects</li> <li>41: <a href="/wiki/Stream_(computing)" title="Stream (computing)">streams</a></li> <li>42: <a href="/wiki/List_comprehension" title="List comprehension">eager comprehensions</a></li> <li>43: vector library</li> <li>45: primitives for expressing iterative lazy algorithms</li> <li>60: integers as bits</li> <li>61: a more general cond clause</li> <li>66: octet vectors</li> <li>67: compare procedures</li></ul> <div class="mw-heading mw-heading2"><h2 id="Implementations">Implementations</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=30" title="Edit section: Implementations">edit</a>]</div> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1236090951"><div role="note" class="hatnote navigation-not-searchable">Main category: <a href="/wiki/Category:Scheme_(programming_language)_implementations" title="Category:Scheme (programming language) implementations">Scheme (programming language) implementations</a></div> The elegant, minimalist design has made Scheme a popular target for language designers, hobbyists, and educators, and because of its small size, that of a typical <a href="/wiki/Interpreter_(computing)" title="Interpreter (computing)">interpreter</a>, it is also a popular choice for <a href="/wiki/Embedded_system" title="Embedded system">embedded systems</a> and <a href="/wiki/Scripting_language" title="Scripting language">scripting</a>. This has resulted in scores of implementations,<a href="#cite_note-scheme_implementations-34">[34]</a> most of which differ from each other so much that porting programs from one implementation to another is quite difficult, and the small size of the standard language means that writing a useful program of any great complexity in standard, portable Scheme is almost impossible.<a href="#cite_note-position_paper-14">[14]</a> The R6RS standard specifies a much broader language, in an attempt to broaden its appeal to programmers. Almost all implementations provide a traditional Lisp-style <a href="/wiki/Read%E2%80%93eval%E2%80%93print_loop" title="Read–eval–print loop">read–eval–print loop</a> for development and debugging. Many also <a href="/wiki/Compiler" title="Compiler">compile</a> Scheme programs to executable binary. Support for embedding Scheme code in programs written in other languages is also common, as the relative simplicity of Scheme implementations makes it a popular choice for adding scripting capabilities to larger systems developed in languages such as <a href="/wiki/C_(programming_language)" title="C (programming language)">C</a>. The <a href="/wiki/Gambit_(Scheme_implementation)" title="Gambit (Scheme implementation)">Gambit</a>, <a href="/wiki/Chicken_(Scheme_implementation)" title="Chicken (Scheme implementation)">Chicken</a>, and <a href="/wiki/Bigloo" title="Bigloo">Bigloo</a> Scheme interpreters compile Scheme to C, which makes embedding far easier. Further, Bigloo's compiler can be configured to generate <a href="/wiki/Bytecode" title="Bytecode">bytecode</a> for the <a href="/wiki/Java_virtual_machine" title="Java virtual machine">Java virtual machine</a> (JVM), and has an experimental bytecode generator for <a href="/wiki/.NET" title=".NET">.NET</a>. Some implementations support added features. For example, <a href="/wiki/Kawa_(Scheme_implementation)" title="Kawa (Scheme implementation)">Kawa</a> and <a href="/wiki/JScheme" title="JScheme">JScheme</a> provide integration with <a href="/wiki/Java_(programming_language)" title="Java (programming language)">Java</a> classes, and the Scheme to C compilers often make it easy to use external libraries written in C, up to allowing the embedding of C code in the Scheme source code. Another example is Pvts, which offers a set of visual tools that support Scheme learning. <div class="mw-heading mw-heading2"><h2 id="Usage">Usage</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=31" title="Edit section: Usage">edit</a>]</div> Scheme is widely used by several<a href="#cite_note-schemers_inc-35">[35]</a> schools; in particular, several introductory <a href="/wiki/Computer_science" title="Computer science">computer science</a> courses use Scheme in conjunction with the textbook <a href="/wiki/Structure_and_Interpretation_of_Computer_Programs" title="Structure and Interpretation of Computer Programs">Structure and Interpretation of Computer Programs</a> (SICP).<a href="#cite_note-sicp_adopters-36">[36]</a> For the past 12 years, <a href="/wiki/Racket_(programming_language)" title="Racket (programming language)">PLT</a> has run the <a href="/wiki/ProgramByDesign" title="ProgramByDesign">ProgramByDesign</a> (formerly TeachScheme!) project, which has exposed close to 600 high school teachers and thousands of high school students to rudimentary Scheme programming. <a href="/wiki/MIT" class="mw-redirect" title="MIT">MIT</a>'s old introductory programming class 6.001 was taught in Scheme,<a href="#cite_note-6.001-37">[37]</a> Although 6.001 has been replaced by more modern courses, SICP continues to be taught at MIT.<a href="#cite_note-6.001_zombies-38">[38]</a> Likewise, the introductory class at <a href="/wiki/UC_Berkeley" class="mw-redirect" title="UC Berkeley">UC Berkeley</a>, CS 61A, was until 2011 taught entirely in Scheme, save minor diversions into <a href="/wiki/Logo_(programming_language)" title="Logo (programming language)">Logo</a> to demonstrate dynamic scope. Today, like MIT, Berkeley has replaced the syllabus with a more modern version that is primarily taught in <a href="/wiki/Python_(programming_language)" title="Python (programming language)">Python 3</a>, but the current syllabus is still based on the old curriculum, and parts of the class are still taught in Scheme.<a href="#cite_note-61A-39">[39]</a> The textbook <a href="/wiki/How_to_Design_Programs" title="How to Design Programs">How to Design Programs</a> by Matthias Felleisen, currently at Northeastern University, is used by some institutes of higher education for their introductory computer science courses. Both <a href="/wiki/Northeastern_University" title="Northeastern University">Northeastern University</a> and <a href="/wiki/Worcester_Polytechnic_Institute" title="Worcester Polytechnic Institute">Worcester Polytechnic Institute</a> use Scheme exclusively for their introductory courses Fundamentals of Computer Science (CS2500) and Introduction to Program Design (CS1101), respectively.<a href="#cite_note-neu-40">[40]</a><a href="#cite_note-wpi-41">[41]</a> <a href="/wiki/Rose-Hulman" class="mw-redirect" title="Rose-Hulman">Rose-Hulman</a> uses Scheme in its more advanced Programming Language Concepts course.<a href="#cite_note-rhit-42">[42]</a> <a href="/wiki/Brandeis_University" title="Brandeis University">Brandeis University</a>'s core course, Structure and Interpretations of Computer Programs (COSI121b), is also taught exclusively in Scheme by theoretical computer scientist <a href="/wiki/Harry_Mairson" title="Harry Mairson">Harry Mairson</a>.<a href="#cite_note-brandeis-43">[43]</a> <a href="/wiki/Indiana_University" title="Indiana University">Indiana University</a>'s introductory class, C211, is taught entirely in Scheme. A self-paced version of the course, CS 61AS, continues to use Scheme.<a href="#cite_note-44">[44]</a> The introductory computer science courses at <a href="/wiki/Yale" class="mw-redirect" title="Yale">Yale</a> and <a href="/wiki/Grinnell_College" title="Grinnell College">Grinnell College</a> are also taught in Scheme.<a href="#cite_note-yale_cs201-45">[45]</a> Programming Design Paradigms,<a href="#cite_note-neu2-46">[46]</a> a mandatory course for the Computer science Graduate Students at <a href="/wiki/Northeastern_University" title="Northeastern University">Northeastern University</a>, also extensively uses Scheme. The former introductory computer science course at the University of Minnesota - Twin Cities, CSCI 1901, also used Scheme as its primary language, followed by a course that introduced students to the Java language;<a href="#cite_note-umn-47">[47]</a> however, following the example of MIT, the department replaced 1901 with the Python-based CSCI 1133,<a href="#cite_note-umn2-48">[48]</a> while functional programming is covered in detail in the third-semester course CSCI 2041.<a href="#cite_note-umn3-49">[49]</a> Scheme is/was also used for the following: <ul><li>The <a href="/wiki/Document_Style_Semantics_and_Specification_Language" title="Document Style Semantics and Specification Language">Document Style Semantics and Specification Language</a> (DSSSL), which provides a method of specifying <a href="/wiki/SGML" class="mw-redirect" title="SGML">SGML</a> <a href="/wiki/Style_sheet_(web_development)" title="Style sheet (web development)">stylesheets</a>, uses a Scheme subset.<a href="#cite_note-dsssl-50">[50]</a></li> <li>The well-known <a href="/wiki/Open-source_software" title="Open-source software">open source</a> <a href="/wiki/Raster_graphics_editor" title="Raster graphics editor">raster graphics editor</a> <a href="/wiki/GIMP" title="GIMP">GIMP</a> uses <a href="/wiki/TinyScheme" title="TinyScheme">TinyScheme</a> as a <a href="/wiki/Scripting_language" title="Scripting language">scripting language</a>.<a href="#cite_note-gimp-51">[51]</a></li> <li><a href="/wiki/GNU_Guile" title="GNU Guile">Guile</a> has been adopted by <a href="/wiki/GNU" title="GNU">GNU</a> project as its official scripting language, and that implementation of Scheme is embedded in such applications as <a href="/wiki/GNU_LilyPond" class="mw-redirect" title="GNU LilyPond">GNU LilyPond</a> and <a href="/wiki/GnuCash" title="GnuCash">GnuCash</a> as a scripting language for extensions. Likewise, Guile used to be the scripting language for the <a href="/wiki/Desktop_environment" title="Desktop environment">desktop environment</a> <a href="/wiki/GNOME" title="GNOME">GNOME</a>,<a href="#cite_note-archive_gnomefaq-52">[52]</a> and GNOME still has a project that provides Guile bindings to its library stack.<a href="#cite_note-live_gnome-53">[53]</a> There is a project to incorporate Guile into <a href="/wiki/GNU_Emacs" title="GNU Emacs">GNU Emacs</a>, GNU's flagship program, replacing the current <a href="/wiki/Emacs_Lisp" title="Emacs Lisp">Emacs Lisp</a> interpreter.[<a href="/wiki/Wikipedia:Citation_needed" title="Wikipedia:Citation needed">citation needed</a>]</li> <li><a href="/wiki/Extension_Language_Kit" title="Extension Language Kit">Elk Scheme</a> is used by <a href="/wiki/Synopsys" title="Synopsys">Synopsys</a> as a scripting language for its <a href="/wiki/Technology_CAD" title="Technology CAD">technology CAD (TCAD)</a> tools.<a href="#cite_note-tcad-54">[54]</a></li> <li>Shiro Kawai, senior programmer on the movie <a href="/wiki/Final_Fantasy:_The_Spirits_Within" title="Final Fantasy: The Spirits Within">Final Fantasy: The Spirits Within</a>, used Scheme as a scripting language for managing the real-time rendering engine.<a href="#cite_note-shiro_kawai-55">[55]</a></li> <li><a href="/wiki/Google_App_Inventor" class="mw-redirect" title="Google App Inventor">Google App Inventor</a> for <a href="/wiki/Android_(operating_system)" title="Android (operating system)">Android</a> uses Scheme, where <a href="/wiki/Kawa_(Scheme_implementation)" title="Kawa (Scheme implementation)">Kawa</a> is used to compile the Scheme code down to bytecodes for the <a href="/wiki/Java_virtual_machine" title="Java virtual machine">Java virtual machine</a> running on Android devices.<a href="#cite_note-android-56">[56]</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=32" title="Edit section: See also">edit</a>]</div> <style data-mw-deduplicate="TemplateStyles:r1239009302">.mw-parser-output .portalbox{padding:0;margin:0.5em 0;display:table;box-sizing:border-box;max-width:175px;list-style:none}.mw-parser-output .portalborder{border:1px solid var(--border-color-base,#a2a9b1);padding:0.1em;background:var(--background-color-neutral-subtle,#f8f9fa)}.mw-parser-output .portalbox-entry{display:table-row;font-size:85%;line-height:110%;height:1.9em;font-style:italic;font-weight:bold}.mw-parser-output .portalbox-image{display:table-cell;padding:0.2em;vertical-align:middle;text-align:center}.mw-parser-output .portalbox-link{display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle}@media(min-width:720px){.mw-parser-output .portalleft{clear:left;float:left;margin:0.5em 1em 0.5em 0}.mw-parser-output .portalright{clear:right;float:right;margin:0.5em 0 0.5em 1em}}</style><ul role="navigation" aria-label="Portals" class="noprint portalbox portalborder portalright"> <li class="portalbox-entry"><a href="/wiki/File:Octicons-terminal.svg" class="mw-file-description"><img alt="icon" src="//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Octicons-terminal.svg/24px-Octicons-terminal.svg.png" decoding="async" width="24" height="28" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Octicons-terminal.svg/37px-Octicons-terminal.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Octicons-terminal.svg/49px-Octicons-terminal.svg.png 2x" data-file-width="896" data-file-height="1024" /></a><a href="/wiki/Portal:Computer_programming" title="Portal:Computer programming">Computer programming portal</a></li></ul> <ul><li><a href="/wiki/Essentials_of_Programming_Languages" title="Essentials of Programming Languages">Essentials of Programming Languages</a>, textbook using Scheme as foundation</li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=33" title="Edit section: References">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 reflist-columns references-column-width" style="column-width: 30em;"> <ol class="references"> <li id="cite_note-1"><a href="#cite_ref-1">^</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 class="citation web cs1"><a rel="nofollow" class="external text" href="https://doc.rust-lang.org/reference/influences.html">"Influences - The Rust Reference"</a>. 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Journal of Functional Programming. 24 (6): 675–716. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1017%2FS0956796814000203">10.1017/S0956796814000203</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:40001845">40001845</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Journal+of+Functional+Programming&rft.atitle=A+run-time+representation+of+scheme+record+types&rft.volume=24&rft.issue=6&rft.pages=675-716&rft.date=2014-11&rft_id=info%3Adoi%2F10.1017%2FS0956796814000203&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A40001845%23id-name%3DS2CID&rft.aulast=Keep&rft.aufirst=Andrew+W.&rft.au=Dybvig%2C+R.+Kent&rft_id=https%3A%2F%2Fdoi.org%2F10.1017%252FS0956796814000203&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-r6rs_Language_changes-11"><a href="#cite_ref-r6rs_Language_changes_11-0">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://www.r6rs.org/final/html/r6rs/r6rs-Z-H-19.html#node_chap_E">"Revised^6 Report on the Algorithmic Language Scheme, Appendix E: language changes"</a>. 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Retrieved 2012-08-09.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=R6RS+Electorate&rft.pub=Scheme+Steering+Committee&rft.date=2007&rft_id=http%3A%2F%2Fwww.r6rs.org%2Fratification%2Felectorate.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-r6rs_feeley-13"><a href="#cite_ref-r6rs_feeley_13-0">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFMarc_Feeley_(compilation)2007" class="citation web cs1">Marc Feeley (compilation) (2007-10-26). <a rel="nofollow" class="external text" href="http://lists.r6rs.org/pipermail/r6rs-discuss/2007-October/003351.html">"Implementors' intentions concerning R6RS"</a>. Scheme Steering Committee, r6rs-discuss mailing list. Retrieved 2012-08-09.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Implementors%27+intentions+concerning+R6RS&rft.pub=Scheme+Steering+Committee%2C+r6rs-discuss+mailing+list&rft.date=2007-10-26&rft.au=Marc+Feeley+%28compilation%29&rft_id=http%3A%2F%2Flists.r6rs.org%2Fpipermail%2Fr6rs-discuss%2F2007-October%2F003351.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-position_paper-14">^ <a href="#cite_ref-position_paper_14-0">a</a> <a href="#cite_ref-position_paper_14-1">b</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWill_Clinger,_Marc_Feeley,_Chris_Hanson,_Jonathan_Rees_and_Olin_Shivers2009" class="citation web cs1">Will Clinger, Marc Feeley, Chris Hanson, Jonathan Rees and Olin Shivers (2009-08-20). <a rel="nofollow" class="external text" href="http://scheme-reports.org/2009/position-statement.html">"Position Statement (draft)"</a>. Scheme Steering Committee. Retrieved 2012-08-09.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Position+Statement+%28draft%29&rft.pub=Scheme+Steering+Committee&rft.date=2009-08-20&rft.au=Will+Clinger%2C+Marc+Feeley%2C+Chris+Hanson%2C+Jonathan+Rees+and+Olin+Shivers&rft_id=http%3A%2F%2Fscheme-reports.org%2F2009%2Fposition-statement.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"><code class="cs1-code">{{<a href="/wiki/Template:Cite_web" title="Template:Cite web">cite web</a>}}</code>: CS1 maint: multiple names: authors list (<a href="/wiki/Category:CS1_maint:_multiple_names:_authors_list" title="Category:CS1 maint: multiple names: authors list">link</a>) </li> <li id="cite_note-r7rs-draft-9-15"><a href="#cite_ref-r7rs-draft-9_15-0">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://trac.sacrideo.us/wg/raw-attachment/wiki/WikiStart/r7rs-draft-9.pdf">"R7RS 9th draft available"</a> (PDF). 2013-04-15.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=R7RS+9th+draft+available&rft.date=2013-04-15&rft_id=http%3A%2F%2Ftrac.sacrideo.us%2Fwg%2Fraw-attachment%2Fwiki%2FWikiStart%2Fr7rs-draft-9.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-r7rs_clinger-16"><a href="#cite_ref-r7rs_clinger_16-0">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWill_Clinger2013" class="citation web cs1">Will Clinger (2013-05-10). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20130721162308/http://lists.scheme-reports.org/pipermail/scheme-reports/2013-May/003401.html">"extension of voting period"</a>. Scheme Language Steering Committee, scheme-reports mailing list. Archived from <a rel="nofollow" class="external text" href="http://lists.scheme-reports.org/pipermail/scheme-reports/2013-May/003401.html">the original</a> on 2013-07-21. Retrieved 2013-07-07.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=extension+of+voting+period&rft.pub=Scheme+Language+Steering+Committee%2C+scheme-reports+mailing+list&rft.date=2013-05-10&rft.au=Will+Clinger&rft_id=http%3A%2F%2Flists.scheme-reports.org%2Fpipermail%2Fscheme-reports%2F2013-May%2F003401.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-easy_to_implement_scheme48-17"><a href="#cite_ref-easy_to_implement_scheme48_17-0">^</a> The <a href="/wiki/Scheme_48" title="Scheme 48">Scheme 48</a> implementation is so-named because the interpreter was written by Richard Kelsey and Jonathan Rees in 48 hours (August 6th – 7th, 1986. 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AI Memos. AIM-349. <a href="/wiki/MIT_Computer_Science_and_Artificial_Intelligence_Laboratory" title="MIT Computer Science and Artificial Intelligence Laboratory">MIT AI Lab</a>. <a href="/wiki/Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<a rel="nofollow" class="external text" href="https://hdl.handle.net/1721.1%2F5794">1721.1/5794</a>. Retrieved 23 December 2021.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=AI+Memos&rft.atitle=Scheme%3A+An+Interpreter+for+Extended+Lambda+Calculus&rft.volume=AIM-349&rft.date=1975-12&rft_id=info%3Ahdl%2F1721.1%2F5794&rft.au=Gerald+Jay+Sussman&rft.au=Guy+Lewis+Steele+Jr.&rft_id=https%3A%2F%2Fdspace.mit.edu%2Fbitstream%2Fhandle%2F1721.1%2F5794%2FAIM-349.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-Moses-19"><a href="#cite_ref-Moses_19-0">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFJoel_Moses1970" class="citation cs2"><a href="/wiki/Joel_Moses" title="Joel Moses">Joel Moses</a> (June 1970), The Function of FUNCTION in LISP, or Why the FUNARG Problem Should Be Called the Environment Problem, <a href="/wiki/Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<a rel="nofollow" class="external text" href="https://hdl.handle.net/1721.1%2F5854">1721.1/5854</a>, <a href="/wiki/AI_Memo" title="AI Memo">AI Memo</a> 199, <q>A useful metaphor for the difference between FUNCTION and QUOTE in LISP is to think of QUOTE as a porous or an open covering of the function since free variables escape to the current environment. FUNCTION acts as a closed or nonporous covering (hence the term "closure" used by Landin). Thus we talk of "open" Lambda expressions (functions in LISP are usually Lambda expressions) and "closed" Lambda expressions. [...] My interest in the environment problem began while Landin, who had a deep understanding of the problem, visited MIT during 1966-67. I then realized the correspondence between the FUNARG lists which are the results of the evaluation of "closed" Lambda expressions in <a href="/wiki/LISP_1.5" class="mw-redirect" title="LISP 1.5">LISP</a> and <a href="/wiki/ISWIM" title="ISWIM">ISWIM</a>'s Lambda Closures.</q></cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=The+Function+of+FUNCTION+in+LISP%2C+or+Why+the+FUNARG+Problem+Should+Be+Called+the+Environment+Problem&rft.date=1970-06&rft_id=info%3Ahdl%2F1721.1%2F5854&rft.au=Joel+Moses&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-20"><a href="#cite_ref-20">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFvan_Tonder2004" class="citation journal cs1">van Tonder, André (1 January 2004). "A Lambda Calculus for Quantum Computation". 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(November 2006). <a rel="nofollow" class="external text" href="https://hal.inria.fr/inria-00090434/file/0.pdf">"A concurrent lambda calculus with futures"</a> (PDF). Theoretical Computer Science. 364 (3): 338–356. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1016%2Fj.tcs.2006.08.016">10.1016/j.tcs.2006.08.016</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Theoretical+Computer+Science&rft.atitle=A+concurrent+lambda+calculus+with+futures&rft.volume=364&rft.issue=3&rft.pages=338-356&rft.date=2006-11&rft_id=info%3Adoi%2F10.1016%2Fj.tcs.2006.08.016&rft.aulast=Niehren&rft.aufirst=J.&rft.au=Schwinghammer%2C+J.&rft.au=Smolka%2C+G.&rft_id=https%3A%2F%2Fhal.inria.fr%2Finria-00090434%2Ffile%2F0.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-lambda_paper_2-22"><a href="#cite_ref-lambda_paper_2_22-0">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGerald_Jay_SussmanGuy_Lewis_Steele_Jr.1976" class="citation journal cs1 cs1-prop-long-vol">Gerald Jay Sussman & Guy Lewis Steele Jr. (March 1976). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160510140804/http://library.readscheme.org/page1.html">"Lambda: The Ultimate Imperative"</a>. AI Memos. AIM-353. <a href="/wiki/MIT_Computer_Science_and_Artificial_Intelligence_Laboratory" title="MIT Computer Science and Artificial Intelligence Laboratory">MIT AI Lab</a>. Archived from <a rel="nofollow" class="external text" href="http://library.readscheme.org/page1.html">the original</a> (postscript or PDF) on 2016-05-10. Retrieved 2012-08-09.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=AI+Memos&rft.atitle=Lambda%3A+The+Ultimate+Imperative&rft.volume=AIM-353&rft.date=1976-03&rft.au=Gerald+Jay+Sussman&rft.au=Guy+Lewis+Steele+Jr.&rft_id=http%3A%2F%2Flibrary.readscheme.org%2Fpage1.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-23"><a href="#cite_ref-23">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGabrielPitman1988" class="citation news cs1"><a href="/wiki/Richard_P._Gabriel" title="Richard P. Gabriel">Gabriel, Richard P.</a>; <a href="/wiki/Kent_Pitman" title="Kent Pitman">Pitman, Kent</a> (1988). <a rel="nofollow" class="external text" href="http://www.nhplace.com/kent/Papers/Technical-Issues.html">"Technical Issues of Separation in Function Cells and Value Cells"</a>. LISP and Symbolic Computation. Vol. 1, no. 1 (published June 1988). pp. 81–101. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2FBF01806178">10.1007/BF01806178</a>. Retrieved 2012-08-09.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=LISP+and+Symbolic+Computation&rft.atitle=Technical+Issues+of+Separation+in+Function+Cells+and+Value+Cells&rft.volume=1&rft.issue=1&rft.pages=81-101&rft.date=1988&rft_id=info%3Adoi%2F10.1007%2FBF01806178&rft.aulast=Gabriel&rft.aufirst=Richard+P.&rft.au=Pitman%2C+Kent&rft_id=http%3A%2F%2Fwww.nhplace.com%2Fkent%2FPapers%2FTechnical-Issues.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-srfi-41-24">^ <a href="#cite_ref-srfi-41_24-0">a</a> <a href="#cite_ref-srfi-41_24-1">b</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFPhilip_L._Bewig2008" class="citation web cs1">Philip L. Bewig (2008-01-24). <a rel="nofollow" class="external text" href="http://srfi.schemers.org/srfi-41/srfi-41.html">"SRFI 41: Streams"</a>. The SRFI Editors, schemers.org. Retrieved 2012-08-09.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=SRFI+41%3A+Streams&rft.pub=The+SRFI+Editors%2C+schemers.org&rft.date=2008-01-24&rft.au=Philip+L.+Bewig&rft_id=http%3A%2F%2Fsrfi.schemers.org%2Fsrfi-41%2Fsrfi-41.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-r4rs-25"><a href="#cite_ref-r4rs_25-0">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWilliam_Clinger_and_Jonathan_Rees1991" class="citation journal cs1">William Clinger and Jonathan Rees, ed. (1991). <a rel="nofollow" class="external text" href="http://www.cs.indiana.edu/scheme-repository/R4RS/r4rs_toc.html">"Revised4 Report on the Algorithmic Language Scheme"</a>. ACM Lisp Pointers. 4 (3): 1–55. Retrieved 2012-08-09.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=ACM+Lisp+Pointers&rft.atitle=Revised%3Csup%3E4%3C%2Fsup%3E+Report+on+the+Algorithmic+Language+Scheme&rft.volume=4&rft.issue=3&rft.pages=1-55&rft.date=1991&rft_id=http%3A%2F%2Fwww.cs.indiana.edu%2Fscheme-repository%2FR4RS%2Fr4rs_toc.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-26"><a href="#cite_ref-26">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFFlatt2016" class="citation book cs1">Flatt, Matthew (2016). "Binding as sets of scopes". 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Retrieved 2012-08-09.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=SRFI+62%3A+S-expression+comments&rft.pub=The+SRFI+Editors%2C+schemers.org&rft.date=2005-07-21&rft.au=Taylor+Campbell&rft_id=http%3A%2F%2Fsrfi.schemers.org%2Fsrfi-62%2Fsrfi-62.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> <li id="cite_note-srfi-6-29"><a href="#cite_ref-srfi-6_29-0">^</a> <link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFWilliam_D_Clinger1999" class="citation web cs1">William D Clinger (1999-07-01). <a rel="nofollow" class="external text" href="http://srfi.schemers.org/srfi-6/srfi-6.html">"SRFI 6: Basic String Ports"</a>. The SRFI Editors, schemers.org. 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ACM SIGPLAN Notices. 21 (12): 37–79. <a href="/wiki/CiteSeerX_(identifier)" class="mw-redirect" title="CiteSeerX (identifier)">CiteSeerX</a> <a rel="nofollow" class="external text" href="https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.29.3015">10.1.1.29.3015</a>. <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%2F15042.15043">10.1145/15042.15043</a>. <a href="/wiki/Hdl_(identifier)" class="mw-redirect" title="Hdl (identifier)">hdl</a>:<a rel="nofollow" class="external text" href="https://hdl.handle.net/1721.1%2F6424">1721.1/6424</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:43884422">43884422</a>. 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Retrieved 2012-08-09.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=Under+the+Hood+of+App+Inventor+for+Android&rft.pub=Google+Inc%2C+Official+Google+Research+blog&rft.date=2009-08-11&rft.au=Bill+Magnuson&rft.au=Hal+Abelson&rft.au=Mark+Friedman&rft_id=http%3A%2F%2Fgoogleresearch.blogspot.com%2F2009%2F08%2Funder-hood-of-app-inventor-for-android.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"> </li> </ol></div> <div class="mw-heading mw-heading2"><h2 id="Further_reading">Further reading</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=34" title="Edit section: Further reading">edit</a>]</div> <ul><li><a rel="nofollow" class="external text" href="ftp://ftp.cs.utexas.edu/pub/garbage/cs345/schintro-v14/schintro_toc.html">An Introduction to Scheme and its Implementation</a> (<a rel="nofollow" class="external text" href="http://icem-www.folkwang-hochschule.de/~finnendahl/cm_kurse/doc/schintro/schintro_toc.html">a mirror</a>)</li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFChristopher_T._Haynes1999" class="citation web cs1">Christopher T. Haynes (1999-06-22). <a rel="nofollow" class="external text" href="http://acm.org/tsc/sstd.html">"The Scheme Programming Language Standardization Experience"</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+Scheme+Programming+Language+Standardization+Experience&rft.date=1999-06-22&rft.au=Christopher+T.+Haynes&rft_id=http%3A%2F%2Facm.org%2Ftsc%2Fsstd.html&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGuy_L._Steele_Jr.,_Richard_P._Gabriel" class="citation web cs1"><a href="/wiki/Guy_L._Steele_Jr." title="Guy L. Steele Jr.">Guy L. Steele Jr.</a>, <a href="/wiki/Richard_P._Gabriel" title="Richard P. Gabriel">Richard P. Gabriel</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20160611055324/http://www.dreamsongs.org/Files/HOPL2-Uncut.pdf">"The Evolution of Lisp"</a> (PDF). Archived from <a rel="nofollow" class="external text" href="http://www.dreamsongs.org/Files/HOPL2-Uncut.pdf">the original</a> (PDF) on 2016-06-11.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=The+Evolution+of+Lisp&rft.au=Guy+L.+Steele+Jr.%2C+Richard+P.+Gabriel&rft_id=http%3A%2F%2Fwww.dreamsongs.org%2FFiles%2FHOPL2-Uncut.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"></li> <li><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFGerald_Jay_SussmanGuy_Lewis_Steele_Jr.1975" class="citation cs1 cs1-prop-long-vol"><a href="/wiki/Gerald_Sussman" class="mw-redirect" title="Gerald Sussman">Gerald Jay Sussman</a> & <a href="/wiki/Guy_Steele" class="mw-redirect" title="Guy Steele">Guy Lewis Steele Jr.</a> (December 1975). <a class="external text" href="https://en.wikisource.org/wiki/Scheme:_An_Interpreter_for_Extended_Lambda_Calculus">Scheme: An Interpreter for Extended Lambda Calculus </a>. Vol. AI Memo 349. <a href="/wiki/MIT_Computer_Science_and_Artificial_Intelligence_Laboratory" title="MIT Computer Science and Artificial Intelligence Laboratory">MIT Artificial Intelligence Lab</a>. <a href="/wiki/CiteSeerX_(identifier)" class="mw-redirect" title="CiteSeerX (identifier)">CiteSeerX</a> <a rel="nofollow" class="external text" href="https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.128.80">10.1.1.128.80</a> – via <a href="/wiki/Wikisource" title="Wikisource">Wikisource</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Scheme%3A+An+Interpreter+for+Extended+Lambda+Calculus&rft.pub=MIT+Artificial+Intelligence+Lab&rft.date=1975-12&rft_id=https%3A%2F%2Fciteseerx.ist.psu.edu%2Fviewdoc%2Fsummary%3Fdoi%3D10.1.1.128.80%23id-name%3DCiteSeerX&rft.au=Gerald+Jay+Sussman&rft.au=Guy+Lewis+Steele+Jr.&rfr_id=info%3Asid%2Fen.wikipedia.org%3AScheme+%28programming+language%29" class="Z3988"></li></ul> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2>[<a href="/w/index.php?title=Scheme_(programming_language)&action=edit&section=35" title="Edit section: External links">edit</a>]</div> <ul><li><a rel="nofollow" class="external text" href="https://scheme.org/">scheme.org</a> provides links to many Scheme resources, including the specifications</li> <li><a href="/wiki/File:Wikibooks-logo-en-noslogan.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/16px-Wikibooks-logo-en-noslogan.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/24px-Wikibooks-logo-en-noslogan.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/32px-Wikibooks-logo-en-noslogan.svg.png 2x" data-file-width="400" data-file-height="400" /></a> <a href="https://en.wikibooks.org/wiki/Scheme_Programming" class="extiw" title="wikibooks:Scheme Programming">Scheme Programming</a> at Wikibooks</li> <li><a rel="nofollow" class="external text" href="https://lips.js.org/docs/category/introduction-to-scheme">Introduction to Scheme</a></li> <li><a href="/wiki/File:Wikibooks-logo-en-noslogan.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/16px-Wikibooks-logo-en-noslogan.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/24px-Wikibooks-logo-en-noslogan.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/df/Wikibooks-logo-en-noslogan.svg/32px-Wikibooks-logo-en-noslogan.svg.png 2x" data-file-width="400" data-file-height="400" /></a> <a href="https://en.wikibooks.org/wiki/Write_Yourself_a_Scheme_in_48_Hours" class="extiw" title="wikibooks:Write Yourself a Scheme in 48 Hours">Write Yourself a Scheme in 48 Hours</a> at Wikibooks</li> <li><a href="/wiki/File:Commons-logo.svg" class="mw-file-description"><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/12px-Commons-logo.svg.png" decoding="async" width="12" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/18px-Commons-logo.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/24px-Commons-logo.svg.png 2x" data-file-width="1024" data-file-height="1376" /></a> Media related to <a href="https://commons.wikimedia.org/wiki/Category:Scheme_(programming_language)" class="extiw" title="commons:Category:Scheme (programming language)">Scheme (programming language)</a> at Wikimedia Commons</li> <li><a rel="nofollow" class="external text" href="https://discu.eu/weekly/lisp/">Scheme Weekly</a></li> <li><a rel="nofollow" class="external text" href="https://lips.js.org/#bookmark">Bookmarklet that add Interactive Scheme REPL to any website</a></li></ul> <div class="navbox-styles"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1129693374"><style data-mw-deduplicate="TemplateStyles:r1236075235">.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output .navbox-subgroup{background-color:#fdfdfd}.mw-parser-output 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<ul><li><a href="/wiki/Garbage_collection_(computer_science)" title="Garbage collection (computer science)">Automatic storage management</a></li> <li><a href="/wiki/Conditional_(computer_programming)" title="Conditional (computer programming)">Conditionals</a></li> <li><a href="/wiki/Dynamic_typing" class="mw-redirect" title="Dynamic typing">Dynamic typing</a></li> <li><a href="/wiki/Higher-order_function" title="Higher-order function">Higher-order functions</a></li> <li><a href="/wiki/Linked_list" title="Linked list">Linked lists</a></li> <li><a href="/wiki/Macro_(computer_science)" title="Macro (computer science)">Macros</a></li> <li><a href="/wiki/M-expression" title="M-expression">M-expressions</a> (deprecated)</li> <li><a href="/wiki/Read%E2%80%93eval%E2%80%93print_loop" title="Read–eval–print loop">Read–eval–print loop</a></li> <li><a href="/wiki/Recursion_(computer_science)" title="Recursion (computer science)">Recursion</a></li> <li><a href="/wiki/S-expression" title="S-expression">S-expressions</a></li> <li><a href="/wiki/Self-hosting_(compilers)" title="Self-hosting (compilers)">Self-hosting</a> <a href="/wiki/Compiler" title="Compiler">compiler</a></li> <li><a href="/wiki/Tree_data_structure" class="mw-redirect" title="Tree data structure">Tree data structures</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Object-oriented_programming" title="Object-oriented programming">Object</a> systems</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/Common_Lisp_Object_System" title="Common Lisp Object System">Common Lisp Object System</a> (CLOS)</li> <li><a href="/wiki/CommonLoops" title="CommonLoops">CommonLoops</a></li> <li><a href="/wiki/Flavors_(programming_language)" title="Flavors (programming language)">Flavors</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/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">Standardized</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/Common_Lisp" title="Common Lisp">Common Lisp</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/Allegro_Common_Lisp" title="Allegro Common Lisp">Allegro Common Lisp</a></li> <li><a href="/wiki/Armed_Bear_Common_Lisp" class="mw-redirect" title="Armed Bear Common Lisp">Armed Bear Common Lisp</a> (ABCL)</li> <li><a href="/wiki/CLISP" title="CLISP">CLISP</a></li> <li><a href="/wiki/Clozure_CL" title="Clozure CL">Clozure CL</a></li> <li><a href="/wiki/CMU_Common_Lisp" title="CMU Common Lisp">CMU Common Lisp</a> (CMUCL)</li> <li><a href="/wiki/Corman_Common_Lisp" class="mw-redirect" title="Corman Common Lisp">Corman Common Lisp</a></li> <li><a href="/wiki/Embeddable_Common_Lisp" title="Embeddable Common Lisp">Embeddable Common Lisp</a> (ECL)</li> <li><a href="/wiki/GNU_Common_Lisp" title="GNU Common Lisp">GNU Common Lisp</a> (GCL)</li> <li><a href="/wiki/LispWorks" title="LispWorks">LispWorks</a></li> <li><a href="/wiki/Macintosh_Common_Lisp" title="Macintosh Common Lisp">Macintosh Common Lisp</a></li> <li><a href="/wiki/Mocl" title="Mocl">Mocl</a></li> <li>Movitz</li> <li><a href="/wiki/Poplog" title="Poplog">Poplog</a></li> <li><a href="/wiki/Steel_Bank_Common_Lisp" title="Steel Bank Common Lisp">Steel Bank Common Lisp</a> (SBCL)</li> <li><a href="/wiki/Genera_(operating_system)" title="Genera (operating system)">Symbolics Common Lisp</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a class="mw-selflink selflink">Scheme</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/History_of_the_Scheme_programming_language" title="History of the Scheme programming language">History</a></li> <li><a href="/wiki/Bigloo" title="Bigloo">Bigloo</a></li> <li><a href="/wiki/Chez_Scheme" title="Chez Scheme">Chez Scheme</a></li> <li><a href="/wiki/Chicken_(Scheme_implementation)" title="Chicken (Scheme implementation)">Chicken</a></li> <li><a href="/wiki/Gambit_(scheme_implementation)" class="mw-redirect" title="Gambit (scheme implementation)">Gambit</a></li> <li><a href="/wiki/Game_Oriented_Assembly_Lisp" title="Game Oriented Assembly Lisp">Game Oriented Assembly Lisp</a> (GOAL)</li> <li><a href="/wiki/GNU_Guile" title="GNU Guile">GNU Guile</a></li> <li><a href="/wiki/Ikarus_(Scheme_implementation)" title="Ikarus (Scheme implementation)">Ikarus</a></li> <li><a href="/wiki/JScheme" title="JScheme">JScheme</a></li> <li><a href="/wiki/Kawa_(Scheme_implementation)" title="Kawa (Scheme implementation)">Kawa</a></li> <li><a href="/wiki/MIT/GNU_Scheme" title="MIT/GNU Scheme">MIT/GNU Scheme</a></li> <li><a href="/wiki/MultiLisp" title="MultiLisp">MultiLisp</a></li> <li><a href="/wiki/Pico_(programming_language)" title="Pico (programming language)">Pico</a></li> <li>Pocket Scheme</li> <li><a href="/wiki/Racket_(programming_language)" title="Racket (programming language)">Racket</a> (<a href="/wiki/Racket_features" title="Racket features">features</a>)</li> <li><a href="/wiki/Scheme_48" title="Scheme 48">Scheme 48</a></li> <li><a href="/wiki/SCM_(Scheme_implementation)" title="SCM (Scheme implementation)">SCM</a></li> <li><a href="/wiki/SIOD" title="SIOD">SIOD</a></li> <li><a href="/wiki/T_(programming_language)" title="T (programming language)">T</a></li> <li><a href="/wiki/TinyScheme" title="TinyScheme">TinyScheme</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/ISLISP" title="ISLISP">ISLISP</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/OpenLisp" title="OpenLisp">OpenLisp</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Unstandardized</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/Logo_(programming_language)" title="Logo (programming language)">Logo</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/MSWLogo" title="MSWLogo">MSWLogo</a></li> <li><a href="/wiki/NetLogo" title="NetLogo">NetLogo</a></li> <li><a href="/wiki/StarLogo" title="StarLogo">StarLogo</a></li> <li><a href="/wiki/UCBLogo" title="UCBLogo">UCBLogo</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/POP-11" title="POP-11">POP</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/COWSEL" title="COWSEL">COWSEL</a> (POP-1)</li> <li><a href="/wiki/POP-2" title="POP-2">POP-2</a></li> <li><a href="/wiki/POP-11" title="POP-11">POP-11</a></li></ul> </div></td></tr></tbody></table><div> <ul><li><a href="/wiki/Arc_(programming_language)" title="Arc (programming language)">Arc</a></li> <li><a href="/wiki/AutoLISP" title="AutoLISP">AutoLISP</a></li> <li><a href="/wiki/BBN_LISP" title="BBN LISP">BBN LISP</a></li> <li><a href="/wiki/Clojure" title="Clojure">Clojure</a></li> <li><a href="/wiki/Dylan_(programming_language)" title="Dylan (programming language)">Dylan</a> (<a href="/wiki/Apple_Dylan" title="Apple Dylan">Apple</a>, <a href="/wiki/History_of_the_Dylan_programming_language" title="History of the Dylan programming language">history</a>)</li> <li><a href="/wiki/Emacs_Lisp" title="Emacs Lisp">Emacs Lisp</a></li> <li><a href="/wiki/EuLisp" title="EuLisp">EuLisp</a></li> <li><a href="/wiki/Franz_Lisp" title="Franz Lisp">Franz Lisp</a>, <a href="/wiki/PC-LISP" title="PC-LISP">PC-LISP</a></li> <li><a href="/wiki/Hy_(programming_language)" title="Hy (programming language)">Hy</a></li> <li><a href="/wiki/Interlisp" title="Interlisp">Interlisp</a></li> <li><a href="/wiki/Knowledge_Engineering_Environment" title="Knowledge Engineering Environment">Knowledge Engineering Environment</a></li> <li><a href="/wiki/*Lisp" title="*Lisp">*Lisp</a></li> <li><a href="/wiki/LeLisp" class="mw-redirect" title="LeLisp">LeLisp</a></li> <li><a href="/wiki/LFE_(programming_language)" title="LFE (programming language)">LFE</a></li> <li><a href="/wiki/Lisp_Machine_Lisp" title="Lisp Machine Lisp">Lisp Machine Lisp</a></li> <li><a href="/wiki/Maclisp" title="Maclisp">Maclisp</a></li> <li><a href="/wiki/MDL_(programming_language)" title="MDL (programming language)">MDL</a></li> <li><a href="/wiki/MLisp" title="MLisp">MLisp</a></li> <li><a href="/wiki/NewLISP" title="NewLISP">newLISP</a></li> <li><a href="/wiki/NIL_(programming_language)" title="NIL (programming language)">NIL</a></li> <li><a href="/wiki/PC-LISP" title="PC-LISP">PC-LISP</a></li> <li><a href="/wiki/Picolisp" class="mw-redirect" title="Picolisp">Picolisp</a></li> <li><a href="/wiki/Portable_Standard_Lisp" title="Portable Standard Lisp">Portable Standard Lisp</a></li> <li><a href="/wiki/RPL_(programming_language)" title="RPL (programming language)">RPL</a></li> <li><a href="/wiki/S-1_Lisp" title="S-1 Lisp">S-1 Lisp</a></li> <li><a href="/wiki/Cadence_SKILL" title="Cadence SKILL">SKILL</a></li> <li><a href="/wiki/Spice_Lisp" title="Spice Lisp">Spice Lisp</a></li> <li><a href="/wiki/Zetalisp" class="mw-redirect" title="Zetalisp">Zetalisp</a></li></ul></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Operating_system" title="Operating system">Operating system</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em"> <li><a href="/wiki/Lisp_(programming_language)#Operating_systems" title="Lisp (programming language)">List</a></li> <li><a href="/wiki/Common_Lisp_Interface_Manager" title="Common Lisp Interface Manager">Common Lisp Interface Manager</a>, <a href="/wiki/McCLIM" title="McCLIM">McCLIM</a></li> <li><a href="/wiki/Genera_(operating_system)" title="Genera (operating system)">Genera</a></li> <li><a href="/wiki/Scsh" title="Scsh">Scsh</a></li> </div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Computer_hardware" title="Computer hardware">Hardware</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/Lisp_machine" title="Lisp machine">Lisp machine</a> <ul><li><a href="/wiki/TI_Explorer" class="mw-redirect" title="TI Explorer">TI Explorer</a></li></ul></li> <li><a href="/wiki/Space-cadet_keyboard" title="Space-cadet keyboard">Space-cadet keyboard</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Community_of_practice" title="Community of practice">Community of practice</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%">Technical standards</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/Scheme_Requests_for_Implementation" title="Scheme Requests for Implementation">Scheme Requests for Implementation</a></li> <li><a href="/wiki/Common_Lisp_HyperSpec" title="Common Lisp HyperSpec">Common Lisp HyperSpec</a></li> <li><a href="/wiki/X3J13" title="X3J13">X3J13</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-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%">Books</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/Common_Lisp_the_Language" title="Common Lisp the Language">Common Lisp the Language</a></li> <li><a href="/wiki/How_to_Design_Programs" title="How to Design Programs">How to Design Programs</a> (HTDP)</li> <li><a href="/wiki/On_Lisp" title="On Lisp">On Lisp</a></li> <li><a href="/wiki/Practical_Common_Lisp" title="Practical Common Lisp">Practical Common Lisp</a></li> <li><a href="/wiki/Structure_and_Interpretation_of_Computer_Programs" title="Structure and Interpretation of Computer Programs">Structure and Interpretation of Computer Programs</a> (SICP)</li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Curriculum</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/ProgramByDesign" title="ProgramByDesign">ProgramByDesign</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr><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%">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/Apple_Inc." title="Apple Inc.">Apple Computer</a></li> <li><a href="/wiki/BBN_Technologies" class="mw-redirect" title="BBN Technologies">Bolt, Beranek and Newman</a></li> <li><a href="/wiki/Harlequin_(software_company)" title="Harlequin (software company)">Harlequin</a></li> <li><a href="/wiki/Lucid_Inc." title="Lucid Inc.">Lucid Inc.</a></li> <li><a href="/wiki/Symbolics" title="Symbolics">Symbolics</a></li> <li><a href="/wiki/Xanalys" title="Xanalys">Xanalys</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/Massachusetts_Institute_of_Technology" title="Massachusetts Institute of Technology">Massachusetts Institute of Technology</a> (MIT)</li> <li><a href="/wiki/MIT_Computer_Science_and_Artificial_Intelligence_Laboratory" title="MIT Computer Science and Artificial Intelligence Laboratory">MIT Computer Science and Artificial Intelligence Laboratory</a> (CSAIL)</li> <li><a href="/wiki/Stanford_University_centers_and_institutes#Stanford_Artificial_Intelligence_Laboratory" title="Stanford University centers and institutes">Stanford Artificial Intelligence Laboratory</a></li> <li><a href="/wiki/University_of_California,_Berkeley" title="University of California, Berkeley">University of California, Berkeley</a></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><td colspan="2" class="navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Edmund_Berkeley" title="Edmund Berkeley">Edmund Berkeley</a></li> <li><a href="/wiki/Daniel_G._Bobrow" title="Daniel G. Bobrow">Daniel G. Bobrow</a></li> <li><a href="/wiki/William_Clinger_(computer_scientist)" title="William Clinger (computer scientist)">William Clinger</a></li> <li><a href="/wiki/R._Kent_Dybvig" title="R. Kent Dybvig">R. Kent Dybvig</a></li> <li><a href="/wiki/Matthias_Felleisen" title="Matthias Felleisen">Matthias Felleisen</a></li> <li><a href="/wiki/Robert_Bruce_Findler" title="Robert Bruce Findler">Robert Bruce Findler</a></li> <li><a href="/wiki/Matthew_Flatt" title="Matthew Flatt">Matthew Flatt</a></li> <li><a href="/wiki/Phyllis_Fox" title="Phyllis Fox">Phyllis Fox</a></li> <li><a href="/wiki/Paul_Graham_(programmer)" title="Paul Graham (programmer)">Paul Graham</a></li> <li><a href="/wiki/Richard_Greenblatt_(programmer)" title="Richard Greenblatt (programmer)">Richard Greenblatt</a></li> <li>Timothy P. Hart</li> <li><a href="/wiki/Louis_Hodes" title="Louis Hodes">Louis Hodes</a></li> <li>Mike Levin</li> <li><a href="/wiki/David_Luckham" title="David Luckham">David Luckham</a></li> <li><a href="/wiki/John_McCarthy_(computer_scientist)" title="John McCarthy (computer scientist)">John McCarthy</a></li> <li><a href="/wiki/Robert_Tappan_Morris" title="Robert Tappan Morris">Robert Tappan Morris</a></li> <li><a href="/wiki/Joel_Moses" title="Joel Moses">Joel Moses</a></li> <li><a href="/wiki/David_Park_(computer_scientist)" title="David Park (computer scientist)">David Park</a></li> <li><a href="/wiki/Steve_Russell_(computer_scientist)" title="Steve Russell (computer scientist)">Steve Russell</a></li> <li><a href="/wiki/Richard_Stallman" title="Richard Stallman">Richard Stallman</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Common_Lisp" title="Common Lisp">Common Lisp</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/Scott_Fahlman" title="Scott Fahlman">Scott Fahlman</a></li> <li><a href="/wiki/Richard_P._Gabriel" title="Richard P. Gabriel">Richard P. Gabriel</a></li> <li><a href="/wiki/Philip_Greenspun" title="Philip Greenspun">Philip Greenspun</a> (<a href="/wiki/Greenspun%27s_tenth_rule" title="Greenspun's tenth rule">10th rule</a>)</li> <li><a href="/wiki/David_A._Moon" title="David A. Moon">David A. Moon</a></li> <li><a href="/wiki/Kent_Pitman" title="Kent Pitman">Kent Pitman</a></li> <li><a href="/wiki/Guy_L._Steele_Jr." title="Guy L. Steele Jr.">Guy L. Steele Jr.</a></li> <li><a href="/wiki/Daniel_Weinreb" title="Daniel Weinreb">Daniel Weinreb</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a class="mw-selflink selflink">Scheme</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/Matthias_Felleisen" title="Matthias Felleisen">Matthias Felleisen</a></li> <li><a href="/wiki/Shriram_Krishnamurthi" title="Shriram Krishnamurthi">Shriram Krishnamurthi</a></li> <li><a href="/wiki/Guy_L._Steele_Jr." title="Guy L. Steele Jr.">Guy L. Steele Jr.</a></li> <li><a href="/wiki/Gerald_Jay_Sussman" title="Gerald Jay Sussman">Gerald Jay Sussman</a></li> <li><a href="/wiki/Julie_Sussman" class="mw-redirect" title="Julie Sussman">Julie Sussman</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/Logo_(programming_language)" title="Logo (programming language)">Logo</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/Hal_Abelson" title="Hal Abelson">Hal Abelson</a></li> <li><a href="/wiki/Denison_Bollay" title="Denison Bollay">Denison Bollay</a></li> <li><a href="/wiki/Wally_Feurzeig" title="Wally Feurzeig">Wally Feurzeig</a></li> <li><a href="/wiki/Brian_Harvey_(lecturer)" title="Brian Harvey (lecturer)">Brian Harvey</a></li> <li><a href="/wiki/Seymour_Papert" title="Seymour Papert">Seymour Papert</a></li> <li><a href="/wiki/Mitchel_Resnick" title="Mitchel Resnick">Mitchel Resnick</a></li> <li><a href="/wiki/Cynthia_Solomon" title="Cynthia Solomon">Cynthia Solomon</a></li></ul> </div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="/wiki/POP-11" title="POP-11">POP</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/Rod_Burstall" title="Rod Burstall">Rod Burstall</a></li> <li><a href="/wiki/Robin_Popplestone" title="Robin Popplestone">Robin Popplestone</a></li></ul> </div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div><img alt="" src="//upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/16px-Symbol_list_class.svg.png" decoding="async" width="16" height="16" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/en/thumb/d/db/Symbol_list_class.svg/23px-Symbol_list_class.svg.png 1.5x, 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