Dan's example fails thus:
| Map.hs:25:19:
| Couldn't match expected type `Nest n1 f b'
|against inferred type `Nest n1 f1 b'
| In the expression: fmap (deepFMap n f)
| In the definition of `deepFMap':
| deepFMap (S n) f = fmap (deepFMap n f)
|
| for reasons I
On Monday 09 March 2009 11:56:14 am Simon Peyton-Jones wrote:
For what it's worth, here's why. Suppose we have
type family N a :: *
f :: forall a. N a - Int
f = blah
g :: forall b. N b - Int
g x = 1 + f x
The defn of 'g' fails with a very similar
