regexps

[Stephen Weeks]

Y'all just saw regexp.mlton, which also contains the beginnings of my new regexp
package for MLton's library.  It does the two stack NFA simulation that Henry
mentioned, as well as compilation to a minimal DFA.  I haven't yet figured out
how to do saves very easily when converting to these forms.  I'll look into it
tomorrow.

Anyways, I'm pretty sure that this is a lot faster than my old package, and once
I get enough functionality in it, I will replace the regexps in mlprof with
these, hopefully speeding up mlprof noticeably.

regexp.mlton is also a cool benchmark because the native codegen produces code
3x faster than the C codegen.  That's the best we've seen so far, I think.

Matthew, I think there is still a bug in mlprof (at least the version I have)
that I see when running on this benchmark.  Remind me and I'll show you
tomorrow.