hello,

i am having trouble getting my program below to work.

i think i implemented the monad methods correctly, but

the function 'g' does not type as i would expect. Hugs

thinks that it is just a list (if i remove the explicit

typing). i want it to be functionally identical to the

function 'h'.

what am i missing?

thanks

konst

> newtype State s a = ST (s -> (a,s))

> unST (ST m) = m

> instance Functor (State s) where
> fmap f m = ST (\s -> let (a,s') = unST m s in (f a, s'))

> instance Monad (State s) where
> return a = ST (\s -> (a,s))
> m >>= f = ST (\s -> let (a,s') = unST m s in unST (f a) s')

> --g :: State String Char
> g = [ x | x <- return 'a' ]

> h :: State String Char
> h = return 'a'