> the following instance declaration doesn't work any
> more with ghc-5.02.3, it worked before.
>
> > newtype ST state a = ST { unST :: state -> (a,state) }
> >
> > instance Monad (ST c) where
> > return x = ST (\state -> (x,state))
> > (m >>= f) = ST (\state -> let (x,state1) = unST m state
> > (y,state2) = unST (f x) state1
> > in (y,state2))
>
> Error message:
> Can't handle multiple methods defined by one pattern binding
> (m >>= f)
> = ST (\ state
> -> let
> (y, state2) = ...
> (x, state1) = ...
> in (y, state2))
>
> What can I do instead?
Remove the parentheses on the left hand side - that's not legal Haskell
98. The error message is a bit cryptic though, the renamer should
really spot that it isn't a valid pattern binding first.
Cheers,
Simon
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