[ Redirected to cvs-ghc because this is very probably not a GLUT problem ]
Mike Thomas wrote:
> CVS ghc on Windows 2000 Pro compiling libraries/GLUT:
> [...]
> Graphics/UI/GLUT/Window.hs:140:
> No instance for (Eq Window)
> arising from use of `==' at Graphics/UI/GLUT/Window.hs:140
> In the predicate expression: w == (Window 0)
> In the second argument of `($)', namely
> `if w == (Window 0) then Nothing else Just w'
> [...]
This can be boiled down to (bleeding edge GHC from CVS, as always):
-- Foo.hs ------------------------------------------------------------
module Foo where
import Foreign.C.Types
newtype Window = Window CInt deriving ( Eq )
----------------------------------------------------------------------
panne@jeanluc:~> ghc -c Foo.hs
Foo.hs:3:
No instance for (Eq GHC.Int.Int32)
arising from the instance declaration at Foo.hs:3
In the instance declaration for `Eq Window'
----------------------------------------------------------------------
Something must have happened to GHC's deriving and/or interface
mechanism in the last month or so. I was on holiday during that
time and Window.hs is more than 2 months old, so I have a rather
good alibi... >:-)
Any clues?
Cheers,
S.
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