I store a matrix as a list of rows, where each row is a list of column
values for that row. I want to check if there is a column in the
matrix that satisfies a comparator `p`

.

`p`

can actually return any non-`#f`

value and that value is returned
as-is. And the lists don't actually have to represent a matrix: the
rows don't all need to have the same number of columns.

`(`*define* (find-stride p . a*)
(letrec
((car-of
(*lambda* (a)
(map car a)))
(cdr-of
(*lambda* (a)
(map cdr a)))
(any-null
(*lambda* (a)
(memq '() a)))
(find*
(*lambda* (a*)
(and (not (any-null a*))
(or (apply p (car-of a*))
(find* (cdr-of a*)))))))
(find* a*)))

Credit: Nils M. Holm (ref: exists.scm)

```
(find-stride < '(9 1) '(8 2) '(7 3))
;; ==> #t ; because (< 1 2 3)
```