Re: [Haskell-cafe] Why distinct tyvars in instance declarations?

On 6/27/05, robert dockins wrote:

I think that you are mistaken. The OP listed:

...

class Foo a instance Foo (Either b b)

Without further information, Haskell compilers will assume that the type(s) in a class declaration has/have kind * (Report section 4.6). Either b b does have kind *, so that's not the problem.

Indeed.

class Foo a

instance Foo (Either b c)

*is* accepted, so this is not a kind error. Josh Hoyt