[erlang-questions] regular expressions (again :)

Richard A. O'Keefe ok@REDACTED
Thu Dec 14 02:13:58 CET 2006


Gaspar Chilingarov <nm@REDACTED> wrote:
	In most text-processing tasks you do not need exactly same
	regexp second time.

Whaaaat?  When I use AWK, my regular expressions may get applied
MILLIONS of times!  I want them compiled just once, thank you very much!

More generally, people who have been brainwashed by AWK and Perl think
of a regular expression as a kind of TOKEN instead of as a kind of
EXPRESSION.  If you have a language (like SNOBOL) in which concatenation
and alternation and so on a genuine operators that can be applied to
computed values, then you very often find that one pattern can be used
*as a building block* in making many other patterns.

I note that having a regular expression compiler that returns a function
is a popular approach in Scheme.




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