On Mon, 12 Feb 2001, Jerzy Karczmarczuk wrote:
I not only feel the need, but I feel that this is important that the additive structure in the codomain is inherited by functions.
It could support only the basic arithmetic. It would not automatically lift an expression which uses (>) and if. It would be inconsistent to provide a shortcut for a specific case, where generally it must be explicitly lifted anyway. Note that it does make sense to lift (>) and if, only the type system does not permit it implicitly because a type is fixed to Bool. Lifting is so easy to do manually that I would definitely not constrain the whole Prelude class system only to have convenient lifting of basic arithmetic. When it happens that an instance of an otherwise sane class for functions makes sense, then OK, but nothing more. -- Marcin 'Qrczak' Kowalczyk