[racket] Combining iteration and match

From: Stephen Chang (stchang at ccs.neu.edu)
Date: Fri Sep 6 19:40:41 EDT 2013

> The 2-3x estimate was for runtime, in the case of for loops with many
> iterations (ie millions). I've just pushed some optimizations though
> that cut the slowdown to maybe 1.5-2x, in preliminary experiments. So
> you should "pkg update" (or pull if you are using the source directly)
> to get the changes.

I've updated the generic-bind ~for/X forms so that its performance is
the same as racket's for/X.

The update relies on a change to racket though. So if you want to try
it, first pull from racket git head, then update the generic-bind pkg.


>
> In addition, you should expect a noticeable compile-time slowdown,
> though I dont have a firm grasp on how much.
>
> By the way, if you are matching lists, you can use the list-match
> binding form directly, to eliminate an extra pair of parens:
>
>   (~for/list ([($list a b) some-sequence])
>     a)
>
> Please keep me updated with any problems you have.
>
>
>
>>
>> Konrad.
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