From: Permjacov Evgeniy <permeakra@gmail.com>

Hi. I Wrote a simple iteration library. It was not intensively tested,
so it MAY contatin bugs, but it is very unlikely. The library is
currently on github: https://github.com/permeakra/iteration

I'm not ready to upload it to hackage, as some testing and extension is
really needed. However, I'd like to know about possible flaws.

Current goal is addition of byte-stream (de)compression and IO functions
extenstion. After this package will be cabalized and uploaded to
hackage. So, while design is not frozen yet, I'm interested in criticism -)/

First, I haven't examined your code in sufficient depth to fully understand it, so I may be off the mark with this comment.  However, I'm not convinced it's possible to safely implement zipping in iteration-style IO without another technique (e.g. monadic regions), by which I mean I suspect any code which exposes enough control to pause an enumeration (or alternatively allows a user-supplied termination check to the enumerator) will also not provide guaranteed finalization/garbage collection of the underlying resource (e.g. handle).

I also require zipping of streams, and in fact it is possible with iteratee.  I haven't included the code in the library because I was formerly not convinced of its safety.  I do think it's safe now, but only by use of a monadic region.

John