[Haskell-cafe] Could not deduce .. why ?

Daniel Fischer daniel.is.fischer at web.de
Sun Oct 12 12:16:12 EDT 2008


Am Sonntag, 12. Oktober 2008 17:38 schrieb Marc Weber:
> Surely I've overseen a small point. But I can't see it:
> Why doesn't ghc recognize taht elc_ (class decl), elc (instance decl) and
> elc_1 are the same type To help you find the connecting pieces faster I've
> marked them with ## ##
>
> Marc
>
>
> data PT a b = PT b -- phantom type containing state a and the result b
>
> class AddEl el_ el2_ elc_ where
>   addEl :: el_ -> elc -> el2_ -- el, child
		   ^^^^^^
I suspect that might be responsible, didn't you mean to write elc_ there?




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