Francois Maltey <[EMAIL PROTECTED]> writes:
> Martin almost convinces me that the algebraic
> [f (u,v) for (u,v) in [a,b,c] X [1,2,3]]
> is better than [f (u,v) for u in [a,b,c] repeat for v in [1,2,3]]
>
> but I expect a syntax suggar and automatic coerce.
It occurred to me that the following might make it even clearer:
what does a looping construct have to do with a Cartesian product? Except that
one may (but doesn't have to) use it to *implement* a function that returns all
elements of a Cartesian product.
> The * isn't the better operator because this locks
> {1,2,3} * {1,2,3} = {1,2,3,4,6,9}
> and {1,2,3} + {1,2,3} = {2,3,4,5,6}
I actually wondered already once, why "+" is not union$Set, "-" not
difference$Set. I didn't think of the possibility above, although I doubt that
it would be too useful. After all, you can even define it only if the elements
understand "+" and "*".
Martin
_______________________________________________
Axiom-math mailing list
[email protected]
http://lists.nongnu.org/mailman/listinfo/axiom-math
