[Haskell-cafe] Attoparsec concatenating combinator
mblazevic at stilo.com
Fri Jun 3 15:50:51 CEST 2011
On 11-06-03 06:00 AM, Yitzchak Gale wrote:
> Mario Blažević wrote:
>> I don't know if this helps, but the incremental-parser library has
>> exactly the combinator you're looking for.
> Wow, that is a beautiful implementation of a general parser
> library. So much simpler than Parsec. Thanks for pointing it out.
Thanks. I guess I should get to work fixing its deficiencies then.
> Why are you hiding those nice Monoid classes in the parser
> package? Shouldn't it be a separate package?
I considered it, and I'll do it if there's interest, but for the first
release I decided to keep them close to where they're needed. There was
less work that way. I'd hate to release a standalone package with only
half the instance implementations.
> Edward Kmett has also been adding some nice Monoid
> abstractions lately. I haven't been following all of it. I wonder
> how yours and his relate.
If you mean semigroups, they are related but only through Monoid.
Semigroup is a superclass of Monoid, whereas CancellativeMonoid and
FunctorialMonoid are its subclasses. CancellativeMonoid is lying between
a Monoid and Group in power. It would make more sense to merge my
classes into some group package, though I don't see any obvious
candidate on Hackage right now.
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