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Postings from January 2004
A thought occurred to me. What should this return:
[1,2,3] »+« [4,5,6]
At first glance, one might say [5,7,9]. But is that really the best
way to go? I'm beginning to think that it should be the same as
whatever [1,2,3]+[4,5,6] is, hopefully an error.
Here's my reasoning. Substitute $a = [1,2,3] and $b = [4,5,6]. Those
are list I<references>, after all. So now it becomes:
$a »+« $b
That might just be okay, since they're both listrefs, and you shouldn't
expect a vector on two scalars to do much besides dereference its
arguments. But now, instead of $a, use the real list (1,2,3):
(1,2,3) »+« $b
That looks extremely different from before. That looks like it's adding
$b to each of (1,2,3). Not only that, but say you have:
$x »+« $y
$x is a number, and $y is a listref. Extrapolating from before, you'd
think that this should add $x to each of $y's elements. But this is
starting to feel like run-time DWIMmery, which is almost always a Bad
Idea (favoring syntactic DWIMmery).
So I'm going to argue that:
[1,2,3] »+« [4,5,6]
either give an error because you can't add listrefs, or give a "useless
use of vector operation on two scalars" error. And if you want what
we originally thought, use:
(1,2,3) »+« (4,5,6)
@$a »+« @$b
$x »+« @$y
Luke
à
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