Lisp
In plain wordsA programming language invented in 1958 for AI research, in which programs and data are written the same way, as nested lists in parentheses. It was the main language of AI for decades.
A family of programming languages descended from John McCarthyJohn McCarthy, prop. n.: The American computer scientist who coined the term 'artificial intelligence', invented the Lisp programming language and championed formal logic as the route to machine common sense.'s 1958 design, in which both data and programs are symbolic expressions (S-expressions) — nested, parenthesized lists — so that programs can build, inspect and run other programs, a property called homoiconicity. Lisp introduced or popularized recursion as a basic control structure, conditional expressions, dynamic typing, automatic garbage collection, the read–eval–print loop and functions as values. Its ease in manipulating symbols made it the dominant language of symbolic AIsymbolic AI, n.: An approach to AI that writes knowledge down as human-readable symbols and rules, such as 'every bird has wings', and reasons by manipulating them step by step instead of learning patterns from data. in the United States from the 1960s to the 1980s, used for systems such as SHRDLUSHRDLU, prop. n.: A program from around 1970 that let people move toy blocks in a simulated world by typing ordinary English commands and questions, and that could explain what it had done and why. and MYCINMYCIN, prop. n.: A 1970s Stanford program that advised doctors on blood infections and antibiotics by applying hundreds of if–then rules from specialists. It performed about as well as experts but was never used on patients., and it inspired dedicated Lisp machinesLisp machine, n.: A 1970s–1980s personal workstation built specially to run the AI programming language Lisp quickly. When ordinary computers caught up, the market collapsed, helping to bring on an AI winter.. Major dialects include Maclisp, Interlisp, Scheme (1975), Common Lisp (ANSI standard 1994), Emacs Lisp and Clojure (2007).
Before Python, an AI course would have had students writing search programs in Lisp.
Origin
Designed by John McCarthy at MIT in 1958 and described in 'Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I' (Communications of the ACM, 1960). The name abbreviates 'LISt Processor'. Steve Russell saw that McCarthy's theoretical eval function could be implemented directly and wrote the first interpreter, for the IBM 704.
Usage note
Of the high-level programming languages still in use, only Fortran (1957) is older. In AI it gave way to C++, Java and, from the 2010s, Python.
Related
- symbolic AIsymbolic AI, n.: An approach to AI that writes knowledge down as human-readable symbols and rules, such as 'every bird has wings', and reasons by manipulating them step by step instead of learning patterns from data.
- Lisp machineLisp machine, n.: A 1970s–1980s personal workstation built specially to run the AI programming language Lisp quickly. When ordinary computers caught up, the market collapsed, helping to bring on an AI winter.
- PrologProlog, prop. n.: A programming language from 1972 in which you state facts and rules in logic and then ask questions; the computer finds answers by searching for proofs.
- John McCarthyJohn McCarthy, prop. n.: The American computer scientist who coined the term 'artificial intelligence', invented the Lisp programming language and championed formal logic as the route to machine common sense.
- AI winterAI winter, n.: A slump in which disappointment over AI's unmet promises leads governments and companies to pull back money and attention. Historians count two big ones: one in the 1970s and one starting in the late 1980s.
- logic programminglogic programming, n.: A style of programming in which you write down facts and rules in logic and then ask questions; the computer works out the answers itself by logical deduction.
Sources
- McCarthy, J. (1960). Recursive Functions of Symbolic Expressions and Their Computation by Machine, Part I. Communications of the ACM 3(4), 184–195.
Mentioned in
John McCarthyJohn McCarthy, prop. n.: The American computer scientist who coined the term 'artificial intelligence', invented the Lisp programming language and championed formal logic as the route to machine common sense., Peter NorvigPeter Norvig, prop. n.: An American computer scientist who co-wrote the standard AI textbook, led research at Google, and helped show that simple methods trained on huge amounts of data often beat clever hand-built ones., PrologProlog, prop. n.: A programming language from 1972 in which you state facts and rules in logic and then ask questions; the computer finds answers by searching for proofs., Lisp machineLisp machine, n.: A 1970s–1980s personal workstation built specially to run the AI programming language Lisp quickly. When ordinary computers caught up, the market collapsed, helping to bring on an AI winter., MIT AI LabMIT AI Lab, prop. n.: The artificial intelligence laboratory at the Massachusetts Institute of Technology, founded in 1959 and one of the birthplaces of AI and hacker culture; it is now part of MIT's computer science lab, CSAIL., Planning Domain Definition LanguagePlanning Domain Definition Language, prop. n.: A standard computer language for describing planning problems — the available actions, the starting situation and the goal — so that any automated planner can read and solve them.