MonadFail Proposal

Note: this proposal page has been moved to the Haskell Prime Wiki.

A quick summary for migration purposes, here are the versions of GHC/base with major developments in the proposal:

8.0.1 (May 2016) / base 4.9.0.0

MonadFail in Control.Monad.Fail added

8.6.1-8.6.4 (all 8.6 have same base) (Sep 2018) / base 4.12.0.0

Last base to still have Monad(fail)

8.8.1 (Jul 2019) / base 4.13.0.0

Migration completed, Monad(fail) gone. MonadFail exported in Prelude.[1]