Re: Lisp history: IF, etc.

Paul Rubin <no.email@nospam.invalid> writes:

Lawrence D'Oliveiro <ldo@nz.invalid> writes:

Was it a matter of timing, then? Perl came along at just the point where
the hardware was powerful enough to take the complexities of regular
expressions in its stride, so that’s when the whole idea really took off.

>
Unix had regular expressions because Thompson's QED editor on some weird
old GE(?) minicomputer had had them.  It compiled the regexex into
machine code, iirc.  Perl was sort of Awk on steroids and Awk also had
regexes.  I think regexes per se were never very cpu or memory hungry.
>
Snobol and Spitbol didn't have regexes.  They did pattern matching by
brute force backtracking.  By that era though, computers had much more
memory than they did when Lisp 2 was happening.

SNOBOL's patterns were much more "procedural" than REs.  For example,
you could implement Russell's paradox in SNOBOL: a pattern that matches
only those patterns that don't match themselves.

--
Ben.