>>   filter odd [1, 2, 3, 4]
>> It filters out the *even* numbers.
> 
> Yes. And the odd numbers stay behind in the filter. If you filter out 
> coffee grounds, what do you have when you're done? Grounds, or coffee?
> 
> The problem with a real filter is it separates, rather than selects. 
> When you filter coffee, are you filtering the grounds or the drinkable 
> stuff? Neither: you're separating the two.

I still prefer Smalltalk's "select" and "reject". Makes much more sense 
to me. :-P

> I'm kind of surprised "filter" doesn't return both, given it would seem 
> (semantically) fairly easy not to calculate whichever half doesn't get 
> used.

Nope; that's "partition". (Which at least has a sensible name.)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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