On 6/4/07, Stefan O'Rear
On Mon, Jun 04, 2007 at 12:05:56PM -0700, David Fox wrote:
I created this file by simplifying an error I was getting from a program that uses the Javascript types. If you remove the type signatures for f1 and f2 it compiles, but how do I fix the error I get when I compile with the signatures?
module Main where
type CPS c a = (a -> c) -> c
class CNode a data TNode = TNode instance CNode TNode
m :: TNode -> TNode -> Bool m a b = f1 b a $ \_ -> True
f1 :: (CNode a, CNode b) => a -> b -> CPS c a f1 a b f = f2 a b $ \_ -> f a
f2 :: (CNode a, CNode b) => a -> b -> CPS c a f2 a b f = f1 a b $ \_ -> f a
This gives these messages:
yhc -linkcore Browser3.hs Compiling Main ( Browser3.hs ) -- during after type inference/checking Error: No default for Main.CNode at 16:1-16:29.(Id 215,[(Id 200,Id 250)]) Error: No default for Main.CNode at 16:1-16:29.(Id 214,[(Id 200,Id 251)]) Error: No default for Main.CNode at 13:1-13:29.(Id 220,[(Id 200,Id 248)]) Error: No default for Main.CNode at 13:1-13:29.(Id 219,[(Id 200,Id 249)])
You can replace the CNode/TNode and CPS declarations with this:
import DOM.Level1.Html import DOM.Level1.Dom import CPS
same result.
Works fine in both GHC and Hugs. I don't think this bug will be fixed, because the current typechecker is already on the chopping block (see Matthieu's SoC project). So just wait a few months, or help.
Stefan
Where do I see Matthieu's SoC project? I scanned the last six months of the YHC mailing list, maybe I missed it.