2 Aug
2013
2 Aug
'13
6:28 p.m.
Makes sense. +1 * Daniel Gorín <dgorin@dc.uba.ar> [2013-08-02 12:18:11+0200]
Control.Applicative.WrappedMonad allows one to use the Functor and Applicative interfaces of something that is only known to be a Monad but, oddly enough, it hides its Monad interface. The proposal is to add the missing Monad instance.
A typical use case for this instance would be:
f :: Failure String m => T1 -> m T2 f = unwrapMonad . f' where f' x = do ... -- one can also use (<$>), (<*>), etc here
(NB. the Failure class is a subclass of Monad only).
A related proposal for the transformers package would be to add a MonadTrans instance for WrappedMonad as well.
Thanks, Daniel