[Haskell-cafe] Infrastructure for testing the impact of a Functor/Applicative/Monad hierarchy

[harry]

Niklas Hambüchen <mail <at> nh2.me> writes:

> Reading the other thread (Adding Applicative/Functor instances to all
> Monads in GHC) I was wondering if there was infrastructure for testing
> what effect making the often-discussed Functor/Monad change would have:
> How many packages on hackage would break etc.

Some patches for GHC/base are attached to
http://hackage.haskell.org/trac/ghc/ticket/4834. They're a couple of years
old, so they may not apply cleanly, but they might help you in assessing the
impact of such a change.