On Fri, Jul 1, 2011 at 7:38 AM, yi huang <yi.codepla...@gmail.com> wrote:
> Say i want to compose Enumerator ByteString m b and Iteratee Builder > m b, so I try to transform the enum to Enumerator Builder m b, > providing function ByteString -> Builder. It's like implement a > Functor instance for Enumerator. But i failed, there are no way to > make type system happy. > Am I right that there is no Functor instance of Enumerator? I'm pretty sure there is one, but it's a functor over b. So something like: instance Functor (Enumerator a m) I think you want to use an Enumeratee: enumerateeByteStringBuilder :: Enumeratee ByteString Builder m b Check out map :: (a -> b) -> Enumeratee a b m c http://hackage.haskell.org/packages/archive/enumerator/0.4.0.1/doc/html/Data-Enumerator.html#v:map
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