On Mon, Feb 18, 2013 at 11:25 AM, Mike Gran <spk121@yahoo.com> wrote:

From: Noah Lavine <noah.b.lavine@gmail.com>
> I haven't worked with the array functionality, so I might be missing
> something, but I don't see why this is natural for array-ref.

One could imagine a Matlab-like syntax where array-ref has to have
the same number of indices as the underlying array, but, if an
index were replaced with a symbol, it would return a slice.

if np is [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
(array-ref np 1 1) -> 5
(array-ref np 1 :) -> [4, 5, 6]
(array-ref np : 1) -> [[2], [5], [8]]

Yes, that would be cool. But I'm not arguing that we shouldn't have some cool array-slicing functions - I'm just saying that they might belong in a separate function, not in array-ref.

Or maybe that's already in Scheme. I'll admit I've never done matrices
in scheme.

As far as I know, there's no standard Scheme way to do arrays.

I haven't done arrays or matrices in Scheme either, so don't take what I say too seriously. I would like to do it some time, but it'll probably only happen if I need to do a lot of array programming for work some time. I think the only way to get the interface right is to have someone write some serious array-processing software in Guile, and then basically do whatever they say. :-)

Noah