Proposal: Applicative => Monad: Call for consensus

[Conor McBride]

Er, hi...

On 5 Jan 2011, at 11:24, Bas van Dijk wrote:

> On Wed, Jan 5, 2011 at 11:33 AM, Simon Marlow <marlowsd at gmail.com>  
> wrote:
>> Furthermore, we have some significant compatibility issues with  
>> Haskell
>> 98/2010 code.  I wouldn't be in favour of doing this unless we can  
>> retain
>> Haskell 98/2010 compatibility somehow (e.g. with superclass  
>> defaults or
>> class aliases).
>
> It would indeed be really nice to have something like this:
>
> {-# LANGUAGE DefaultInstances #-}
>
> class Functor f where
>    fmap :: (a → b) → f a → f b
>
> class Functor f ⇒ Applicative f where
>    pure  :: a → f a
>    (<*>) :: f (a → b) → f a → f b
>
>    instance Functor f where
>        fmap f m = pure f <*> m

[..]


> Now only someone has to implement it :-)

(ahem)

cabal install she

http://personal.cis.strath.ac.uk/~conor/pub/she/superclass.html

[ducks and runs]

Conor