Re: [Haskell-cafe] A home-brew iteration-alike library: some extension quiestions

Also, one thing that tripped me up is that your "Stream" type is fundamentally different from the "Stream" types in the iteratee/enumerator libraries - yours is more of a monadic list in the inner monad, with explicit errors. How does this change the operation of the Iterator type? I hope I am not pestering you too much :-) I think it is really fascinating how many different approaches people have to the left-fold-enumerator idea, and it is hard for me to grasp which differences are fundamental and what the differences mean. Also, in what way are the other libraries not Haskell-2010 compliant? I haven't experimented too much with this sort of thing, since Cabal defaults to the Haskell '98 language, and that's how I install most things. Thanks for your response, Antoine On Thu, Dec 9, 2010 at 2:07 PM, Permjacov Evgeniy wrote:

On 12/09/2010 10:54 PM, Antoine Latter wrote:

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I only have some surface level questions/comments -

What existing packages is this similar to? How is it different from any previous work in the area?

Main idea was taken from Iteratees invented by Oleg Kiselev (there are two packages on hackage implementing this ideas: data-iteraties and enumerator packages) The difference is, that I wished haskell-2010 compilant package for left-foldable streams, including support for easy builing, transcoding, merging and folding of streams relying on do-notation (see Data.Iteration.Unicode.* for examples of transcoding streams: it is quite clean and easily understandable) and ability to specify easily monadic actions in stream processors.

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Also, likes looks like you don't need the 'Monad m' constraint on your various Monad and Functor instances in Data.Iteration.Types, which I think is one of the nicest properties of the continuation-based approach to something like this. Errgh. That may be true, but I did not consider non-monadic context at all, so I enforced this constrain mindlessly It's a mater of taste which way to go, but I prefer importing modules qualified rather than have type-suffixes on functions - so I would rather use 'I.next' and 'A.next' instead of 'nextI' and 'nextA'. But reasonable people can disagree on this.

Take care, Antoine Thanks! On Thu, Dec 9, 2010 at 1:42 PM, Permjacov Evgeniy wrote:

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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 -)/

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