Re: [Haskell-cafe] Monad for Set?

2007-08-07 Thread Vitaliy Akimov
> > If you also read the rest of that thread, you'll see that with a recent > GHC HEAD, you should be able to avoid the need for the Teq witness. > http://www.cs.chalmers.se/~rjmh/Papers/restricted-datatypes.ps here is solution which doesn't require GADT and HEAD, but it does require changing of m

Re: [Haskell-cafe] Monad for Set?

2007-08-06 Thread Matthew Brecknell
Ronald Guida: > I'm pondering, is it possible to define a Set monad analogous to the > List monad? [snip] > This leads me think of a different solution: What if I could define a > Set monad that's smart enough to "know", for any type a, whether or > not (Eq a) holds, and degenerate to a blind li

[Haskell-cafe] Monad for Set?

2007-08-06 Thread Ronald Guida
Hi, I'm pondering, is it possible to define a Set monad analogous to the List monad? My thinking is as follows: * "fmap f x" would apply f to each element in a set x * "return x" would create a singleton set {x} * "join x", where x is a set of sets: x = {x1, x2, ... xn}, would