[Haskell-cafe] Re: Left fold enumerator - a real pearl overlooked?

John Lato jwlato at gmail.com
Sun Mar 1 16:04:52 EST 2009

Hi Don,

Would you please elaborate on what features or capabilities you think
are missing from left-fold that would elevate it out of the special
purpose category?  I think that the conception is so completely
different from bytestrings that just saying it's not a bytestring
equivalent doesn't give me any ideas as to what would make it more
useful.  Since the technique is being actively developed and
researched, IMO this is a good time to be making changes.

Incidentally, in my package I've made newtypes that read data into
strict bytestrings.  It would be relatively simple to use
unsafeInterleaveIO in an enumerator to create lazy bytestrings using
this technique.  I don't see why anyone would want to do so, however,
since it would have all the negatives of lazy IO and be less efficient
than simply using lazy bytestrings directly.


On Sat, Feb 28, 2009 at 10:54 PM, Don Stewart <dons at galois.com> wrote:

>> There are a few iteratee/enumerator design questions that remain,
>> which Oleg and others would like to explore more fully.  The results
>> of that research will likely find there way into this library.
> I agree. There's no left-fold 'bytestring' equivalent. So it remains a
> special purpose technique.
> -- Don

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