Why do we need Control.Monad.Instances?

[Bas van Dijk]

Hello,

I forgot the reason why we need Control.Monad.Instances which exports
orphaned Functor and Monad instances for ((->) r), ((,) a) and (Either
e):

https://github.com/ghc/packages-base/blob/master/Control/Monad/Instances.hs

Can't we just de-orphan these instances by moving the instances for
((->) r) and ((,) a) to GHC.Base and by moving the instances for
Either to Data.Either?

Regards,

Bas