[Haskell-cafe] Iteratee, parsec & co.

9 Feb 2010

      I read a lot about iteratee IO and it seemed very interesting
(Unfortunately it lacks tutorial). Especially features like 'no input
yet' in network programming (with lazy IO + parsec I run into problems
as it tried to evaluate the first response character before sending
output).

I decided first write a simple program and then attempt write a Stream
implementation for parsec.
...
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
import Data.Iteratee
import Text.Parse
data Buffer a = Buffer
instance Monad m => Stream (Buffer a) (IterateeG [] a m) a where
    uncons Buffer = IterateeG loop
                    where loop (Chunk [])     =
                              return $! Cont (IterateeG loop) Nothing
                          loop (Chunk (x:xs)) =
                              return $! Done (Just (x, Buffer))
                                             (Chunk xs)
                          loop (EOF Nothing)  =
                              return $! Done Nothing (EOF Nothing)
                          loop (EOF (Just e)) =
                              return $! throwErr e
1. I'm not quite sure what Cursor was suppose to do from A Parsing
Trifecta presentation.

2. Is there any package which contains this stream definition?

3. Why Seek FileOffset is error message?

Regards

PS. I guess iteratee does qualify as cafe but if beginner would be more
appropriate group then I'm sorry - I'll remember next time.

[Haskell-cafe] Iteratee, parsec & co.

Maciej Piechotka