[Haskell-cafe] Altering Class hierarchy

[Stephen Tetley]

The Functor-Applicative-Monad hierarchy change has been a difficult
change _because_ Functor and Monad are primary parts to the Prelude
(standard library). Individual projects don't change the standard
library, so changing a class hierarchy is no more problematic than any
other substantial / breaking change to a code base.

Best wishes

Stephen