Consider rebuilding the concept of matrix around finite sequences instead of tuples

[lowasser]

This is probably more compatible with all the surrounding concepts we will shortly start to need, including permutations, sums, and the like.

[fredrik-bakke]

Supported, but let's not delete the current stuff. It may be useful that we show they're equivalent

[lowasser]

What naming convention would you expect for this versus the tuple based thing?

[fredrik-bakke]

I'm not entirely sure. What do you think of fin-sequence-matrix (or finseq-matrix) vs. tuple-matrix?

[lowasser]

It would certainly make me very sad not to use the unqualified term matrix for the most common, useful version of the thing.