Re: [Haskell-cafe] Question on type synonym definition and language extensions

On Thu, 29 May 2008, Olivier Boudry wrote:

Hi all,

I'm trying to define a type synonym for 2D MArray instances. The goal is to keep the function signature simple and readable using type `Matrix` instead of something like `(Ix i, MArray a e m) => m (a i e)`.

After some "read, guess, try, error" cycles I came up with this:

type Matrix = forall m. forall a. forall i. forall n. (Ix i, MArray a n m, Num i, Num n) => m (a (i,i) n)

Is type Matrix monad array num = monad (array (Int,Int) num) ok for you?