Hello Anatoly, On Sat, Apr 11, 2009 at 20:44, Anatoly Yakovenko <[email protected]>wrote:
> i am trying to understand how data.data works. How would i traverse > the subterms of one type and build another type out of them. > something like this: > > > gmapQ (\a -> Right a) (Just "hello") I am not sure I understand what you're trying to do here. However, in general, 'gmapQ' is used in combination with 'mkQ' or 'extQ'. Those are not in Data.Data: you can import Data.Generics to get everything syb-related. Cheers, Pedro > > > <interactive>:1:0: > Inferred type is less polymorphic than expected > Quantified type variable `d' escapes > In the first argument of `gmapQ', namely `(\ a -> Right a)' > In the expression: gmapQ (\ a -> Right a) (Just "hello") > In the definition of `it': > it = gmapQ (\ a -> Right a) (Just "hello") > > > Thanks, > Anatoly > _______________________________________________ > Haskell-Cafe mailing list > [email protected] > http://www.haskell.org/mailman/listinfo/haskell-cafe >
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