On 01/03/11 17:30, Bas van Dijk wrote:
... The patch for base makes a few changes:
1) Make Applicative a superclass of Monad. So the new hierarchy becomes:
2) Make 'join' a method of Monad. ... class Applicative m => Monad m where ... (>>) :: forall a b. m a -> m b -> m b (>>) = (*>)
The former/current default definition of (>>) was based on (>>=), not (*>) (which if itself is undefined, itself defaults to (fmap (const id) a <*> b). That's a change. You also added defaults for most of the Monad methods, though they're obvious and I approve. The (>>) default might have worse performance than the previous default though? (>>) is used in do-notation desugaring, and yet many (most?) Monad instance writers do not explicitly define it, so its default makes some difference. Does anyone know how to test? -Isaac