Library-vs-local performance

Don Stewart dons at
Tue Jun 24 15:50:45 EDT 2008

>    Hi,
>    I've got a library that I'm in the process of uploading to hackage
>    (waiting for account) but the darcs repo is here:
>    [1]
>    I notice a slight drop in performance when I install the library using
>    cabal. Maybe 10-20%, on one particular function. This is in comparison to
>    when the library is 'local', as in, the source files are in the same
>    directory as the client application.

Lack of unfolding and inlining when compiled in a package? Try compiling
with -O2, for maximum unfolding.
>    What could be causing the performance drop? The function in question
>    requires impractical amounts of inlining (This is something of an
>    experiment), but I don't see how installing it as a library affects that.
>    The functions to be inlined are small, surely available in the .hi files.

You can check this via -show-iface
>    Its only when they are applied do they agglomerate into a big mess -
>    80-200K lines of core.
>    The function in question is invertMany in examples/Examples.hs.

-- Don

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