Re: multidim. containers

At 10:28 AM 8/28/00 +1000, Jeremy Howard wrote:
><X-posted to [email protected]>
>
>David L. Nicol wrote:
> > If arrays as we know them implement by using a key space restricted to
> > integers, I think a reasonable way to get matrices would be to open
> > up their key space to lists of integers.
> >
>I've been thinking along exactly the same lines. There's a lot of language
>issues to consider to get this to work consistently, such as interaction
>with reduce(), notation for slices across a dimension (and generalised
>slices such as diagonals), and so forth.
>
>I'm thinking that a n-dim array could just be a list of lists (of lists of
>lists of...) with the n-dim notation just being syntactic sugar (and perhaps
>helping with optimisation too).

If you want efficiency, n-dimensional arrays really need to be a concrete 
data type all of their own. That way one big block of memory can be 
allocated and, if it's a typed array, properly sized.

That doesn't mean that n-dimensional arrays won't be just sugar over the 
standard list-o-list structure to start, but they won't have to stay that way.

					Dan

--------------------------------------"it's like this"-------------------
Dan Sugalski                          even samurai
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                                      teddy bears get drunk