Re: #4159: move Monad and MonadFix instances for Either from mtl to base

Iavor Diatchki schrieb:

Hello, I don't mind the instance being in MTL because then I can choose if I should use it or not.

You cannot really choose - if only one imported package transitively depends on MTL you get that instance. Dependencies on Hackage are so big today, that it is very likely to get MTL or transformers imported that way.