[Haskell] Re: Crazy class stuff

Taral taralx at gmail.com
Tue Mar 13 03:54:27 EDT 2007

On 3/13/07, Taral <taralx at gmail.com> wrote:
> And it doesn't work. I know what I want it to do, how do I express it right?

This is closer, but still doesn't work:

class (Monad i, Monad o) => MonadTrans' i o where
    lift' :: i a -> o a

instance Monad m => MonadTrans' m m where
    lift' = id

instance (MonadTrans t, MonadTrans' a b) => MonadTrans' a (t b) where
    lift' = lift . lift'

Taral <taralx at gmail.com>
"You can't prove anything."
    -- Gödel's Incompetence Theorem

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