[Haskell-cafe] "mapping" an Enumerator

I'm using the Data.Enumerator library. I'm trying to write a "map" function that converts an Enumerator of one type to another. Something like: mapEnum :: Monad m => (a -> b) -> Enumerator a m r -> Enumerator b m r Any hints? (My exact use case is that I have a ByteString enumerator and I need to pass it to something that requires a Blaze.Builder enumerator.)