24 Jan
2008
24 Jan
'08
4:31 p.m.
On Thu, Jan 24, 2008 at 10:06:04AM -0600, Antoine Latter wrote:
Can "Fix" be made to work with higher-kinded types? If so, would the following work:
Perfect = /\ A . Fix (L :: * -> *) . (A + L (A,A))
Hi, Thanks for your quick reply. Unfortunately, your solution does not work. For Fix X. t to be well-defined, we must have that if 'X' has kind 'k', then 't' must also have kind 'k' (compare the type of 'fix' in Haskell: (a -> a) -> a).
Keep in mind I have no idea what the "Perfect" data structure is supposed to look like.
The Haskell equivalent would be data Perfect a = Leaf a | Branch (Perfect (a, a)) and models perfect binary trees (I admit, slightly headwrecking datatype! :) Edsko