29 May
2008
29 May
'08
10:58 a.m.
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. Also, Alternative instances for everything that has a MonadPlus instance.