[Haskell-cafe] Code review: efficiency question

[Josef Svenningsson]

Brian,

You might also want to take a look at the list fusion functionality in
GHC which often can help optimize your programs when programming with
lists.
http://www.haskell.org/ghc/docs/latest/html/users_guide/rewrite-rules.html#id3153234
It doesn't help in your particular program but it might be usable for
you in the future.

Cheers,

/Josef

On 5/3/06, Brian Hulley <brianh at metamilk.com> wrote:
> Bulat Ziganshin wrote:
> > [ideas including reverseMapM_]
> > you will laugh, but speed of your two solutions depends on so many
> > factors (including size of CPU cache) that noone can say that is
> > better in general. although for small lists reverseMapM_ should be
> > faster than reverse+mapM. what will be faster - using of higher-order
> > function or direct recursion, i can't say, it's a really
> > counter-intuitive area of ghc optimizer :)
> >
> > of course, i don't think that all that really matters for your program
> > (drawing should anyway need much more time than looping). just use
> > higher-level approach (that makes code simpler to write, understand
> > and maintain) and don't bother your mind :)
>
> Hi Bulat!
> Thanks for the suggestions about reverseMapM_ etc.
> It seems that since the speeds of the two solutions can be relatively
> faster/slower on different platforms/CPUs I might as well just use the
> combination of existing functions mapM_ and reverse at the moment to get
> readable code with the least amount of effort :-)
>
> Best regards, Brian.
>
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