Re: Monad of no `return` Proposal (MRP): Moving `return` out of `Monad`

Sadly liftM vs. liftA actually retains a useful distinction, one is a definition of fmap in terms of (>>=) and the other in terms of (<*>). `ap` gives a default definition of (<*>) in terms of (>>=), but if someone instead writes (<*>) = liftM2 id today, then erasing the distinction would turn that into a circular definition, transforming obviously-correct existant code silently into a _|_. -Edward On Thu, Sep 24, 2015 at 8:36 PM, Dan Burton wrote:

What about the derived functions in Control.Monad, such as liftM? Shall we similarly relax their constraints to Applicative and consider them "legacy"? (Did this already happen when I wasn't looking?)

On Thursday, September 24, 2015, John Wiegley wrote:

...

...

...

...

...

> Herbert Valerio Riedel writes:

...

TLDR: To complete the AMP, turn `Monad(return)` method into a top-level binding aliasing `Applicative(pure)`.

Very much +1.

John _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

-- -- Dan Burton

_______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries