Re: Generate text, given a regex

> Nonetheless, it's an interesting exercise.  Will probably use it in a
> data structures course some time in the future.  If you want to
> implement the "obvious" recursive solution and still generate every
> possible string, you effectively need coroutines to do alternation.

Or lazy evaluation (same thing).  Doug McIlroy's functional pearl
"Enumerating the strings of regular languages" in JFP (preprint at
http://www.cs.dartmouth.edu/~doug/nfa.ps.gz)
gives elegant Haskell
code to generate texts both directly from the regular expression (the
grammar route) and from the equivalent automaton.

Russ