Hello, I've been playing around with GTK+HS recently. This makes extensive use of Haskell classes, so I sometimes get strange type errors like this one.. textNew (creates a new text widget) has type: textNew :: AdjustmentClass adj => Maybe adj -> Maybe adj -> IO Text But when I try to create one using: txt <- textNew Nothing Nothing GHC complains: Main.hs:82: Ambiguous type variable(s) `a' in the constraint `GtkAdjustment.AdjustmentClass a' arising from use of `textNew' at Main.hs:82 in a `do' expression pattern binding: txt <- textNew Nothing Nothing My first thought was that I need a type signature for txt, but seeing as txt has to be type IO Text, I dont think that's possible (because 'adj' is not referenced). Is that correct? So, what should one do in this situation? Something like this perhaps.. myNothing :: Maybe dummyAdjustmentClassInstance myNothing = Nothing txt <- textNew myNothing myNothing I'm pretty sure that would do it, but it seems like an ugly solution. Is there a better way? Thanks -- Adrian Hey