Re: A Plan for Hacking

[Marijn <hkBst@gentoo.org>]

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Hi Noah,

On 09/26/11 00:33, Noah Lavine wrote:
> I thought of another use-case, and I wonder if you think this is 
> on-topic or not:
> 
> - You write a parallel version of map that is fast, but only
> correct if its argument has no side-effects. You'd like to use this
> parallel map instead of the regular one, but only when it is
> correct.

This seems to assume that map does its thing one element after
another, but that is not what the spec says it does. Note "The dynamic
order in which proc is applied to the elements of the lists is
unspecified." in the below R5RS quote:

(map proc list1 list2 . . . )

The lists must be lists, and proc must be a procedure taking
as many arguments as there are lists and returning a single
value. If more than one list is given, then they must all
be the same length. Map applies proc element-wise to the
elements of the lists and returns a list of the results, in
order. The dynamic order in which proc is applied to the
elements of the lists is unspecified.

Marijn
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