17 Dec
2009
17 Dec
'09
5:22 p.m.
On 17 Dec 2009, at 15:31, Simon Peyton-Jones wrote:
Hmm. If you have class (Diff (D f)) => Diff f where
then if I have f :: Diff f => ... f = e then the constraints available for discharging constraints arising from e are Diff f Diff (D f) Diff (D (D f)) Diff (D (D (D f))) ...
That's a lot of constraints.
But isn't it a bit like having an instance Diff f => Diff (D f) ? Conor