[Antik-devel] nested vector structure

[Liam Healy]

On Fri, Nov 16, 2012 at 9:12 AM, Mirko Vukovic <mirko.vukovic at gmail.com>wrote:

> Liam,
>
> I looked at the code.  I'll take your email as an offer to guide.  And
> you can take this email as an offer to hack.
>
> A few questions:
>
> What type should a vector of vectors be?  Currently, you are
> specializing on lists and arrays.  Should I define a new type, or
> should it be of array type where specify vector of vectors in
> `rest-spec' of make-grid-data?
>

I don't know what you mean.  Types and classes are different things, and
specialization takes place on classes.

My idea is that the specification of a vector of vectors of double-floats
is e.g.
((array 3) (array 4) double-float)
so this would look to CL like something of type array or vector.  There
isn't a need to define a new type, but I suppose you could make one up.
I'm not sure what purpose it would serve.



>
> In the former case, we will have a proliferation of new data structures.
>
> In the latter case, the methods that specialize on array (make-array,
> grid-ref) would have to do some internal testing and then branching
> off.
>

cl:make-array is not anything we can do anything about, it is not a generic
function.
make-grid would need to be generalized to make a multiarray, yes.  There is
work there to be done.  grid-ref is obsolete; you would need to modify
grid:aref, grid:aref*, (setf grid:aref), (setf grid:aref*).  (The file
multiarray.lisp is old and has not been touched in over a year, it was just
a collection point for the temporarily abandoned multiarray code and grid
changes took place without it being modified after that.)


> Are grids meant to be extendable (like vector-push-extend)?  I would
> argue for that capability.
>

That would be nice, but I haven't thought about how to do it.  Also nice
would be to handle displaced arrays and views (subarrays that aren't
actually copied out of the original array).  I think Tamas has done some
work on displaced arrays.

>
> Mirko
>
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