class (Monad m, Monad (t m)) = MonadT t m where
lift :: m a - t m a
instance (Monad m, Monad (StateT s m)) = MonadT (StateT s) m where
lift m = \s - m = \x - return (s,x)
If the definitions from the paper can be turned into valid
Haskell 98 w.l.o.g. now, then I'm happy.
No,
class (Monad m, Monad (t m)) = MonadT t m where
lift :: m a - t m a
instance (Monad m, Monad (StateT s m)) = MonadT (StateT s) m where
lift m = \s - m = \x - return (s,x)
If the definitions from the paper can be turned into valid
Haskell 98 w.l.o.g. now, then I'm happy.
No,
Simon Peyton-Jones [EMAIL PROTECTED] writes
- The simple-context restriction.
...
My default position is not to change. Question: who, apart from
Ralf, has actually tripped over the lack of contexts of the
form (C (a t1 .. tn)) in Haskell 1.4? Is their lack a real
problem in practice?
