Lisp (programming language): Difference between revisions

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{{Multiple image |direction=vertical |image1=John McCarthy Stanford.jpg |image2=Steve Russell.jpg |footer=[[John McCarthy (computer scientist)|John McCarthy]] (top) and [[Steve Russell (computer scientist)|Steve Russell]]}}

[[John McCarthy (computer scientist)|John McCarthy]] began developing Lisp in 1958 while he was at the [[Massachusetts Institute of Technology]] (MIT). He was motivated by a desire to create an AI programming language that would work on the IBM 704, as he believed that "IBM looked like a good bet to pursue Artificial Intelligence research vigorously."<ref name="wexelblat-history-programming-languages>{{cite book |title=History of programming languages |last1=McCarthy |first1=John |last2=Wexelblat |first2=Richard L. |year=1978 |isbn=0127450408 |publisher=Association for Computing Machinery |page=173-183}}</ref> He was influencedinspired by the[[Information designProcessing (andLanguage]], limitations)which ofwas thealso [[Fortran]]based Liston Processinglist Languageprocessing, whichbut implementeddid thenot coreuse ideait ofbecause takingit instructionwas inputdesigned asfor adifferent serieshardware ofand listshe butfound usedan algebraic language more appealing<ref name="wexelblat-history-programming-languages" />. Due to these factors, he consulted on the design of the [[Fortran]] List Processing Language, which was implemented as a hostFortran languagelibrary. McCarthyHowever, he was dissatisfied with this languageit because it did not support [[Recursion (computer science)|recursion]] or a modern [[Conditional (computer programming)#If–then(–else)|if-then-else]] statement (which was a new concept when lisp was first introduced) {{NoteTag|At the time, Fortran had an if-then-else construct that accepted line numbers as jump targets, in the manner of a [[Goto]] statement, rather than accepting arbitrary expression in "then" and "else" blocks}}<ref name="wexelblat-history-programming-languages" />.

[[Information Processing Language]] was the first [[Artificial intelligence|AI]] language, from 1955 or 1956, and already included many of the concepts, such as list-processing and recursion, which came to be used in Lisp.<ref name="wexelblat-history-programming-languages" />

McCarthy's original notation used bracketed "[[M-expression]]s" that would be translated into [[S-expression]]s. As an example, the M-expression {{Lisp2|car[cons[A,B]]}} is equivalent to the S-expression {{Lisp2|(car (cons A B))}}. Once Lisp was implemented, programmers rapidly chose to use S-expressions, and M-expressions were abandoned <ref name="wexelblat-history-programming-languages />. M-expressions surfaced again with short-lived attempts of [[MLisp]]<ref name="Smith">{{cite book |last=Smith |first=David Canfield |title=MLISP Users Manual |url=http://www.softwarepreservation.org/projects/LISP/stanford/Smith-MLISP-AIM-84.pdf |access-date=2006-10-13}}</ref> by Horace Enea and [[CGOL]] by [[Vaughan Pratt]].