28 Sep
2012
28 Sep
'12
8:19 p.m.
On Fri, Sep 28, 2012 at 5:04 PM, Francesco Mazzoli
CCing the list back.
At Fri, 28 Sep 2012 13:30:52 -0700, Alexander Solla wrote:
What is the problem, exactly? It looks to me like UndecidableInstances and ScopedTypeVariables (on foo, or its arguments) would be enough.
I'm not sure what you mean. I don't see the need for UndecidableInstances, and there is no way I can see to bring the `b' into scope in the type sig for foo, ScopedTypeVariables or not - unless I'm missing something.
Well, then what exactly is the problem? Are you getting an error? You don't need to bring 'b' into scope. You will already have real types in scope. instance Foo A B instance Bar A where foo A B = C tryIt = (foo :: A -> B -> C) A B