Re: Generalized newtype deriving 6.6 vs. 6.8

Simon Peyton-Jones wrote:

Well it's debatable. Suppose we have

newtype Foo = MkFoo String deriving( Num )

Do you want to generate

instance Num String => Num Foo

?

Personally, I think I would like that -- along with a warning message. It makes it clearer to me that I can do newtype Foo a = MkFoo a deriving( Num ) without requiring that Foo can only be instantiated with types in Num. I'm not sure though. Isaac