On Wed, 2013-04-24 at 10:56 -0700, Bryan O'Sullivan wrote:
On Wed, Apr 24, 2013 at 10:47 AM, Duncan Coutts < duncan.coutts@googlemail.com> wrote:
I address it briefly in my thesis [1], Section 4.8.2. I think it's a fundamental limitation of stream fusion.
See also concat, where the naive fusion-based implementation has quadratic performance:
concat :: [Text] -> Text concat txts = unstream (Stream.concat (List.map stream txts))
I've never figured out how to implement this with sensible characteristics within the fusion framework.
Well of course concatMap is another issue. I address that in section 4.8.3 :-) Summary there is that I don't think it is a fundamental limitation, but certainly we don't do it properly in practice now. I have a suggestion in that section for how we might do it. Duncan