Re: frantk / overlapping instances

[Anibal Maffioletti Rodrigues de DEUS]

I also was tring to play with frantk, but after the overlapping problem
(that I found a solution in FranTk homepage) I got this problem:

Dependency analysis
ERROR "D:\Programming\Frantk\src\FranTkSrc\WidgetSetImpl.lhs" (line 518):
Undefined qualified variable "T.sameConfig"

Any help ?

____________________________________________
Computer Science Student at UCPel
Pelotas, RS - BRAZIL
EMail: [EMAIL PROTECTED]
Homepage: http://atlas.ucpel.tche.br/~deus/

----- Original Message -----
From: Tom Pledger <[EMAIL PROTECTED]>
To: Timothy Docker <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Thursday, August 31, 2000 11:29 PM
Subject: frantk / overlapping instances


> Timothy Docker writes:
>  >
>  > I'm attempting to play with frantk. I found the same problem mentioned
>  > on deja... but no answer...
>  >
>  > When I try and run the demo under hugs, I get...
>  >
>  > ....
>  > Reading file
"/home/timd/src/haskell/frantk/src/FranTkSrc/WidgetSetImpl.lhs":
>  > ERROR "/home/timd/src/haskell/frantk/src/FranTkSrc/WidgetSetImpl.lhs"
(line 64): Overlapping instances for class "Bindable"
>  > *** This instance   : Bindable Canvas
>  > *** Overlaps with   : Bindable (PWidget a)
>  > *** Common instance : Bindable Canvas
>  >
>  > A suggestion for a direct fix would be nice, but I can't attempt to
>  > work out what the problem is if I don't understand the error. What is
>  > an "overlapping instance"?
>  >
>  > Thanks,
>  >
>  > Tim
>
>
> It means that when the system sees a class method of Bindable (I'm
> guessing there's one called bind) applied to a value of type Canvas
> (which must be a synonym for PWidget something, in order for there to
> be an overlap), it can't tell whether it's supposed to use the
> implementation from `instance Bindable Canvas' or the implementation
> from `instance Bindable (PWidget a)'.
>
> Hugs has an extension which you can enable on the command line, to
> permit overlapping instances as long as one is strictly more specific
> than the other, with the more specific instance's implementations
> taking precedence.  The message "Common instance : Bindable Canvas"
> shows that it's applicable.
>
> HTH
> Tom
>