On Mon, Aug 23, 2010 at 10:37 PM, Conrad Parker <con...@metadecks.org>wrote:
> On 24 August 2010 14:14, Jason Dagit <da...@codersbase.com> wrote: > > I'm not a semanticist, so I apologize right now if I say something stupid > or > > incorrect. > > > > On Mon, Aug 23, 2010 at 9:57 PM, Conal Elliott <co...@conal.net> wrote: > >>> > >>> So perhaps this could be a reasonable semantics? > >>> > >>> Iteratee a = [Char] -> Maybe (a, [Char]) > >> > >> I've been tinkering with this model as well. > >> > >> However, it doesn't really correspond to the iteratee interfaces I've > >> seen, since those interfaces allow an iteratee to notice size and number > of > >> chunks. I suspect this ability is an accidental abstraction leak, which > >> raises the question of how to patch the leak. > > > > From a purely practical viewpoint I feel that treating the chunking as an > > abstraction leak might be missing the point. If you said, you wanted the > > semantics to acknowledge the chunking but be invariant under the size or > > number of the chunks then I would be happier. > > I think that's the point, ie. to specify what the invariants should > be. For example (to paraphrase, very poorly, something Conal wrote on > the whiteboard behind me): > > run [concat [chunk]] == run [chunk] > > ie. the (a, [Char]) you maybe get from running an iteratee over any > partitioning of chunks should be the same, ie. the same as from > running it over the concatenation of all chunks, which is the whole > input [Char]. > I find this notation foreign. I get [Char], that's the Haskell String type, but what is [chunk]? I doubt you mean a list of one element. > > > I use iteratees when I need to be explicit about chunking and when I > don't > > want the resources to "leak outside" of the stream processing. If you > took > > those properties away, I wouldn't want to use it anymore because then it > > would just be an inelegant way to do things. > > Then I suppose the model for Enumerators is different than that for > Iteratees; part of the point of an Enumerator is to control the size > of the chunks, so that needs to be part of the model. An Iteratee, on > the other hand, should not have to know the size of its chunks. So you > don't want to be able to know the length of a chunk (ie. a part of the > stream), but you do want to be able to, say, fold over it, and to be > able to stop the computation at any time (these being the main point > of iteratees ...). > I think I agree with that. Jason
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe