Re: proposal #4095: add Applicative instance for Either

25 May 2010


      On Tue, May 25, 2010 at 07:55:42PM +0200, Bas van Dijk wrote:
...
On Tue, May 25, 2010 at 7:21 PM, Ross Paterson  wrote:
...
Fine by me.  Making it a non-orphan would break Haskell 98 compatibility,
though.
Making it non-orphan means moving the Monad Either instance to either
GHC.Base (which defines the Monad class) or to Data.Either (which
defines the Either type). How exactly does this break Haskell 98
compatibility?
This Haskell 98 module will not be accepted:

module M where
instance Monad (Either a)