[Haskell-cafe] mtlx has a nice design but is slow

[Don Stewart]

Is the package missing some obvious inlining in the instances?

On Wed, Apr 6, 2011 at 10:13 AM, Sean Leather <leather at cs.uu.nl> wrote:
> I just refactored my type and transform system prototype (introduced in [1]
> but changed since then) from using mtlx [2] (type-indexed monad transformers
> described in [3]) to mtl using RWST. mtlx allowed me to cleanly separate the
> various monadic components in a convenient way. Unfortunately, I found it to
> be too slow. The refactoring was an experiment to see how slow. I was rather
> surprised:
>
> Running time of a compiled main with a list of tests:
>   mtlx (7 transformers): 2 min 52 sec
>   mtl (RWST): 0 min 13 sec
>
> It's frustrating to see such a huge performance gap for a better design.
>
> Regards,
> Sean
>
> [1]
> http://splonderzoek.blogspot.com/2011/03/draft-type-changing-program-improvement.html
> [2] http://hackage.haskell.org/package/mtlx
> [3] http://www.ittc.ku.edu/~marks/cgi-bin/pubs/monadfactory.pdf
>
>
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