| In your case the error message was:
|
| GADT.hs:26:56:
| GADT pattern match with non-rigid result type `Maybe a'
| Solution: add a type signature
| In a case alternative: I1 m' - m'
| In the expression: case w' S of { I1 m' - m' }
| In a case alternative: Wrap w' - case
| After installing ghc 6.10-rc, I have a program that
| no longer compiles. I get the dreaded GADT pattern match
| error, instead :)
I'm sorry it's dreaded! Jason is right that the key point is this:
GHC now enforces the rule that in a GADT pattern match
- the type of the scrutinee
Hi, Simon
Thanks a lot for your mail. It turns out I could have resolved this by
myself (with the help of this thread http://thread.gmane.org/gmane.comp.lang.haskell.glasgow.user/15153
, to be honest). What I was missing was this key part:
bind :: forall a b t. W t a - (a - W t b) - W_ t b
dgorin:
I've tried adding some signatures (together with -
XScopedTypeVariables), but with no luck. Why is it that this no longer
compiles? More importantly, how can I make it compile again? :)
If you work out how to make it compile, can you document the soln. here,
On Oct 14, 2008, at 7:48 PM, Don Stewart wrote:
dgorin:
I've tried adding some signatures (together with -
XScopedTypeVariables), but with no luck. Why is it that this no
longer
compiles? More importantly, how can I make it compile again? :)
If you work out how to make it compile, can
On Tue, Oct 14, 2008 at 7:27 AM, Daniel Gorín [EMAIL PROTECTED] wrote:
Hi
After installing ghc 6.10-rc, I have a program that no longer compiles. I
get the dreaded GADT pattern match error, instead :)
Here is a boiled-down example:
{-# OPTIONS_GHC -XGADTs -XEmptyDataDecls #-}
module
