boost for

(cat|girl|gay|boob|shark|emoj(i|o)|gargr?(on|amel))s?

hello i'm one of the seven (7) people in the world who apparently enjoys writing regular expressions enough to shitpost about it

@CobaltVelvet
I enjoy writing regex engines, does that count?

@kellerfuchs @CobaltVelvet I enjoy complaining about how much better regular expressions could be if they were composable, ie http://synthcode.com/scheme/irregex/ (see also http://www.more-magic.net/posts/lispy-dsl-sre.html and for why regexes aren't composable (read "stringly typed systems") see http://groups.csail.mit.edu/mac/users/gjs/6.945/psets/ps01/ )

@cwebber @kellerfuchs @CobaltVelvet Shout-out to probably my favorite published paper ever, "A Play on Regular Expressions": https://sebfisch.github.io/haskell-regexp/

I used that library once to crack the cipher state of badly-encrypted files where the plaintext had a nice regular structure. Each observed byte constrained the possible cipher states a little more, in ways that fit the semiring construction nicely.

@jamey @kellerfuchs @CobaltVelvet holy shit this post has everything

@jamey @CobaltVelvet
Yeah, it's a very nice paper.

IIRC, it's however pretty hard to implement match groups with that approach (and it seems the Haskell library doesn't?), so that's likely a bust for @cwebber

@kellerfuchs @CobaltVelvet @cwebber Yes, you're correct, that library doesn't make it easy to extract parts of the match. I seem to recall that I thought through how to do it, but didn't actually try it because it's hard, and now I don't even remember how it would work.

But there's a paper from the next year's ICFP that extends regex derivatives to context-free parser combinators, so cleverer people than me have that covered!

@jamey @CobaltVelvet @cwebber
IIRC, they already had context-free stuff there, using coinductive (i.e., potentially infinite) structures for regexps.

@kellerfuchs @CobaltVelvet @cwebber Yes, that's correct, but the later paper makes it relatively efficient and, of immediate relevance to this discussion, extends it to parser combinators which can extract a parse tree rather than just recognizing whether an input matches or not.

@jamey @CobaltVelvet @cwebber
*nods.*
If you happen to have a ref. to the paper, that would be great; otherwise, I'll try and remember to hunt it down.