On 5/2/20 10:56 PM, Bradley Lucier wrote:
> APL seems to pun 1 x 1 arrays with scalar values (both ways), and SRFI
> 179 does not do that, so it's not terribly easy to reproduce the other
> example on that page.  But one can calculate the other example as
>
> (define X
>    (list->specialized-array '(1 3 5 7) (make-interval '#(4))))
>
> (define Y
>    (list->specialized-array '(2 3 6 7) (make-interval '#(4))))
>
> (array-reduce + (array-map (lambda (x y) (if (= x y) 1 0)) X Y))
>
> and you get 2, as expected.  (The last expression is pulled out from the
> definition of inner-product.)

One can

(define X
   (list->specialized-array '(1 3 5 7) (make-interval '#(1 4))))

(define Y
   (list->specialized-array '(2 3 6 7) (make-interval '#(4 1))))

(array-display (inner-product X + (lambda (x y) (if (= x y) 1 0)) Y))

which displays 2, the single element of the 1 x 1 array.

Brad