[Haskell-cafe] Could not deduce .. why ?
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 ## ##
> 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?
More information about the Haskell-Cafe