[Haskell-cafe] stream fusion -- multi-module programs

Don Stewart dons at galois.com
Wed Apr 8 12:38:18 EDT 2009

>   In the paper "Stream Fusion: From Streams To Lists To Nothing
>   At All", we find:
>     For large multi-module programs, the results are less clear,
>     with just as many programs speeding up as slowing down. We
>     find that for larger programs, GHC has a tendency to miss
>     optimisation op- portunities for stream fusible functions
>     across module boundaries, which is the subject of further
>     investigation.
>   What's the state of these things? Is this still an issue for
>   stream fusion?

I think it just needs rerunning in light of all the inliner changes 
over the past 2 years. The kinds of programs I write in practice don't
seem to suffer, but I tend not to use concatMap on stream.

-- Don

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