David Menendez wrote:
I wouldn't say that. It's important to remember that Haskell class Monad does not, and can not, represent *all* monads, only (strong) monads built on a functor from the category of Haskell types and functions to itself.
Data.Set is a functor from the category of Haskell types *with decidable ordering* and *order-preserving* functions to itself. That's not the same category, although it is closely related.
I nominate this post for the September 2008 Most Incomprehensible Cafe Post award! :-D Seriously, that sounded like gibberish. (But then, you're talking to somebody who can't figure out the difference between a set and a class, so...) All I know is that sometimes I write stuff in the list monad when the result really ought to be *sets*, not lists, because 1. there is no senamically important ordering 2. there should be no duplicates But Haskell's type system forbids me. (It also forbids me from making Set into a Functor, actually... so no fmap for you!) PS. Text is unpredictable, so just in case... If this post sounds like a flame, it isn't meant to be. ;-)