Daniel Peebles wrote:
Yeah, in a way similar to ArrowPlus/ArrowZero. Then again, I'm not sure whether it would be meaningful to split up MonadPlus like that.
Well, we could always have: class MonadZero m => MonadPlus m The suggestion is just to broaden the scope of mzero so that you can have it without requiring mplus as well (since mplus is much more specific than mzero). If we have a MonadZero, then the call to fail when pattern binds fail could be replaced with calls to mzero (or at the very least, fail can be moved to MonadZero as well to clean up Monad). Then Monad is clean and accurate, and people just depend on MonadZero if they choose to do pattern binds rather than catching all patterns with a case expression. -- Live well, ~wren