Re: [Haskell-cafe] Iteratee performance

As a general style tip, since you're using language extensions anyway

{-# LANGUAGE RankNTypes, ScopedTypeVariables #-}

you might want to add "BangPatterns", so you can put the strictness annotation directly on the argument. Either by doing this: go !n = ... or later on: let !n' = ... return I.Cont ...

cnt = go 0  where   go n = I.IterateeG $ \ch ->       case ch of         (I.EOF Nothing)        -> return $ I.Done n ch         (I.EOF (Just e))       -> return $ I.Cont cnt (Just e)         (I.Chunk (I.WrapBS s)) -> do             let n' = n + S.count '\n' s             return $ n' `seq` I.Cont (go n') Nothing