Most of you have probably read Oleg's essays on using left-fold enumerators for incremental IO. In short, by encapsulating monadic left-folds in an "Iteratee" type, incremental pure processing is possible without using lazy IO. Sources to read: Oleg: Streams and Iteratees < http://okmij.org/ftp/Streams.html > Magnus Therning: Trying to work out iteratees < http://therning.org/magnus/archives/735 > cdsmith: Iteratees Step By Step (Part 1) < http://cdsmith.wordpress.com/2010/05/23/iteratees-step-by-step-part-1/
John Millikin (me): Understanding Iteratees < http://ianen.org/articles/understanding-iteratees/ > Currently, the primary package for left-fold enumerators is John Lato's "iteratee". It is based on Oleg's original code, extended to support various forms of containers, platform-specific IO, and codecs for the WAV and TIFF formats. While I appreciate Mr. Lato's development of the package, I find it far too large, and its documentation too sparse, to effectively use. To correct this, I've written the "enumerator" package. It is also derived from Oleg's IterateeM.hs , but with a simplified API and significantly reduced dependency list. Hackage entry: http://hackage.haskell.org/package/enumerator Haddock docs: http://ianen.org/haskell/enumerator/api-docs/ Source code (literate PDF): http://ianen.org/haskell/enumerator/enumerator.pdf darcs get http://ianen.org/haskell/enumerator/ Additionally, I've included examples of using enumerators to implement simplified versions of the "cat" and "wc" utilities. These should serve as a useful starting point for anybody who wants to use enumerators in their own code: http://patch-tag.com/r/jmillikin/enumerator/snapshot/current/content/pretty/... http://patch-tag.com/r/jmillikin/enumerator/snapshot/current/content/pretty/... There are already a few libraries using the existing "iteratee" package (snap, attoparsec-iteratee, hexpat-iteratee); I am very interested in advice from the authors of these libraries. In particular, are any of the removed features (ListLike, WrappedByteString, seeking) something your libraries depend on? Are there any useful combinators you'd like to see included?