7 Jun
2011
7 Jun
'11
10:24 p.m.
On Tue, Jun 7, 2011 at 16:16, Arnaud Bailly
For example, while designing some program (a game...) I defined a type class thus:
class (Monad io) => CommandIO io where readCommand :: io Command writeResult :: CommandResult -> io ()
This is in fact one of the reasons to use type classes. In fact, you'll find a somewhat more general variety of it on Hackage in a couple of forms, the one I'm most familiar with being MonadPrompt.