it seems that haskell versions of bignums is pretty much gone from more recent discussions of gmp replacements. now, I assume that there are lots of optimizations that keep gmp popular that one wouldn't want to have to reproduce, so that a haskell variant might not be competitive even if one had an efficient representation, but - do all those who want to distribute binaries, but not dynamically linked, need bignums? - it would be nice to know just how far off a good haskell version would be performance-wise.. - what would be a killer for numerical programming, might still be quite acceptable for a substantial part of haskell uses? of course, the real gmp replacement project might be going so well that a haskell version would be obsolete rather sooner than later, and i certainly don't want to interfere with that effort. all that being said, it occurred to me that the representations and fusions described in the nice "rewriting haskell strings" paper would be a good foundation for a haskell bignum project, wouldn't they? http://www.cse.unsw.edu.au/~dons/fps.html http://hackage.haskell.org/trac/ghc/wiki/ReplacingGMPNotes has anyone been looking into this option? just another thought, claus ps. while I'm at it: claiming that "array fusion .. has received comparatively little attention" sounds a bit dangerous to me, and the references are all too limited - even if you meant "in the Haskell world" (and PADL is no Haskell event). you might want to try searching with some other search terms, keeping in mind that most of the work will have been done for not so declarative languages: it isn't my area, but "loop fusion" and "with-loop folding" come to mind, and I'm sure that all those array language and numerical programming folks would be rather, well, disappointed?, to see their efforts ignored like that.