[Haskell-cafe] NB: DO NOT USE `pure = return`

Johannes Waldmann johannes.waldmann at htwk-leipzig.de
Mon Jul 1 19:09:13 UTC 2019

Dear Cafe,

the migration guide (for AMP)


contains this advice:

instance Applicative Foo where
    -- NB: DO NOT USE `pure = return`

Why not? Because it would require another refactoring
once "monad of no return" comes true?

So defining `return` in the Monad instance should work fine until then?
Which is when exactly? I can't quite make it out from

- J.W.

More information about the Haskell-Cafe mailing list