29 May
2008
29 May
'08
2:58 p.m.
On Thu, May 29, 2008 at 03:58:07PM +0100, Ross Paterson wrote:
On Thu, May 29, 2008 at 06:44:12AM -0400, Isaac Dupree wrote:
Spencer Janssen wrote:
This proposal is very straightforward: add Applicative instances for all the Monads in the MTL.
It's not quite as straightforward as it looks: If you only need an instance (Applicative m) => Applicative (Transformer m), not instance (Monad m) => Applicative (Transformer m), will you use the first one? (I think yes.)
Yes, and ditto for the Functor instances, where possible.
Is it worth sacrificing backwards compatibility? We can't guarantee that all Monads are Functors.
Also, Alternative instances for everything that has a MonadPlus instance.
I will add these. Cheers, Spencer Janssen