Hi all,
for my current project I need a monad that is an instance of MonadIO,
MonadReader, MonadWriter, MonadState, and MonadError. I see two ways for
defining such a monad using the mtl.
1) type MyMonad = ErrorT E (RWST R W S IO)
and
2) type MyMonad = RWST R W S (ErrorT E IO)
I can't figure out what is the difference between these two definitions
and therefore which one is more suitable for my problem. Or are the
equivalent and it is unimportant which one I use?
Or is it even better define a new type like
newtype MyMonad a = MyMonad { runMyMonad :: R -> S -> IO (Either E a,S,W) }
and declare instances for all 5 type classes?
Thanks for your help in advance,
Martin.
_______________________________________________
Haskell-Cafe mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/haskell-cafe
