On Wed, 19 May 2021, Johannes Waldmann wrote:
I wanted a really fast implementation of a vector addition system where the "vector" contains small numbers only.
With integer elements?
and I want it packed into a machine word (and finally put these into Data.IntSet).
Why not using Integer? With a bit of bit tricks you can implement a vector add via Integer addition. https://en.wikipedia.org/wiki/SWAR E.g. like this vectorAdd x y = maskOddElements (maskOddElements x + maskOddElements y) + maskEvenElements (maskEvenElements x + maskEvenElements y) But I suspect that larger Integers are not hold in registers. Chances are better for a record of Word8's, Word16's ... Maybe if they are put in a compact region: http://hackage.haskell.org/package/ghc-compact Or you use the CPU vector types that GHC provides. http://hackage.haskell.org/package/ghc-prim-0.7.0/docs/GHC-Prim.html#g:35 There seem to be some packages for small vectors: https://hackage.haskell.org/package/compact-word-vectors https://hackage.haskell.org/package/smallarray