LISP
[from `LISt Processing language', but mythically from
`Lots of Irritating Superfluous Parentheses'] n. AI's mother
tongue, a language based on the ideas of (a) variable-length lists
and trees as fundamental data types, and (b) the interpretation of
code as data and vice-versa. Invented by John McCarthy at MIT in
the late 1950s, it is actually older than any other HLL still
in use except FORTRAN. Accordingly, it has undergone considerable
adaptive radiation over the years; modern variants are quite
different in detail from the original LISP 1.5. The dominant HLL
among hackers until the early 1980s, LISP now shares the throne
with C. See languages of choice.
All LISP functions and programs are expressions that return
values; this, together with the high memory utilization of LISPs,
gave rise to Alan Perlis's famous quip (itself a take on an Oscar
Wilde quote) that "LISP programmers know the value of everything
and the cost of nothing".
One significant application for LISP has been as a proof by example
that most newer languages, such as COBOL and Ada, are full
of unnecessary crocks. When the Right Thing has already
been done once, there is no justification for bogosity in newer
languages.
