Is it time to start deprecating FunDeps?
ekmett at gmail.com
Wed May 1 17:26:09 CEST 2013
Er, what I meant was
class Foo s t a b | s -> a, t -> b, s b -> t, t a -> s
That is what I get for dashing it off off the cuff. =)
Then s determines some type argument for it, t determines its type
argument, but Using s and the other type argument I can determine the whole
containing type 't' and vice versa.
instance Foo (Identity a) (Identity b) a b
On Wed, May 1, 2013 at 7:02 AM, Ian Lynagh <ian at well-typed.com> wrote:
> On Tue, Apr 30, 2013 at 11:35:10PM -0400, Edward Kmett wrote:
> > I have dozens of classes of forms like
> > class Wrapped s t a b | a -> s, b -> t, a t -> s, b s -> t
> Isn't this equivalent to just
> class Wrapped s t a b | a -> s, b -> t
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