[Haskell] [Haskell-cafe] ANNOUNCE: enumerator 0.4.8

[John Millikin]

0.4.9 has been uploaded to cabal, with the new operators. Changes are in the 
replied-to post (and also quoted below), plus the new operators proposed by 
Kazu Yamamoto.

Here's the corresponding docs (they have examples!)

------------------------------------------------------------------------------------------------------
-- | @enum =$ iter = 'joinI' (enum $$ iter)@
--
-- “Wraps” an iteratee /inner/ in an enumeratee /wrapper/.
-- The resulting iteratee will consume /wrapper/’s input type and
-- yield /inner/’s output type.
--
-- Note: if the inner iteratee yields leftover input when it finishes,
-- that extra will be discarded.
--
-- As an example, consider an iteratee that converts a stream of 
UTF8-encoded
-- bytes into a single 'TL.Text':
--
-- > consumeUTF8 :: Monad m => Iteratee ByteString m Text
--
-- It could be written with either 'joinI' or '(=$)':
--
-- > import Data.Enumerator.Text as ET
-- >
-- > consumeUTF8 = joinI (decode utf8 $$ ET.consume)
-- > consumeUTF8 = decode utf8 =$ ET.consume
--
-- Since: 0.4.9

-- | @enum $= enee = 'joinE' enum enee@
--
-- “Wraps” an enumerator /inner/ in an enumeratee /wrapper/.
-- The resulting enumerator will generate /wrapper/’s output type.
--
-- As an example, consider an enumerator that yields line character counts
-- for a text file (e.g. for source code readability checking):
--
-- > enumFileCounts :: FilePath -> Enumerator Int IO b
--
-- It could be written with either 'joinE' or '($=)':
--
-- > import Data.Text as T
-- > import Data.Enumerator.List as EL
-- > import Data.Enumerator.Text as ET
-- >
-- > enumFileCounts path = joinE (enumFile path) (EL.map T.length)
-- > enumFileCounts path = enumFile path $= EL.map T.length
--
-- Since: 0.4.9
------------------------------------------------------------------------------------------------------

Minor release note -- 0.4.9 and 0.4.9.1 are the exact same code; I just 
forgot a @ in one of the new docs and had to re-upload so Hackage would 
haddock properly. There is no difference in behavior.

On Monday, March 28, 2011 10:50:45 PM UTC-7, John Millikin wrote:
>
> Since the release, a couple people have sent in feature requests, so I'm 
> going to put out 0.4.9 in a day or so.
>
> New features will be:
>
> - tryIO: runs an IO computation, and converts any exceptions into 
> ``throwError`` calls (requested by Kazu Yamamoto)
>
> - checkContinue: encapsulates a common pattern (loop (Continue k) = ...) 
> when defining enumerators
>
> - mapAccum and mapAccum: sort of like map and mapM, except the step 
> function is stateful (requested by Long Huynh Huu)
>
> Anyone else out there sitting on a request? Please send them in -- I am 
> always happy to receive them, even if they must be declined.
>
> ---
>
> Also, I would like to do a quick poll regarding operators.
>
> 1. It has been requested that I add operator aliases for joinI and joinE.
>
> 2. There have been complaints that the library defines too many operators 
> (currently, 5).
>
> Do any existing enumerator users, or anyone for that matter, have an 
> opinion either way?
>
> The proposed operators are:
>
> ----------------------------------------------------------------------
> infixr 0 =$
> infixr 0 $=
>
> (=$) :: Monad m => Enumeratee ao ai m b -> Iteratee ai m b -> Iteratee ao m 
> b
> enum =$ iter = joinI (enum $$ iter)
>
> ($=) :: Monad m => Enumerator ao m (Step ai m b) -> Enumeratee ao ai m b -> 
> Enumerator ai m b
> ($=) = joinE
> ----------------------------------------------------------------------
>
>
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