racket: equivalent to np.zeros((n, m))

I can't understand what I'm doing wrong here. Maybe a misplaced backquote.

The racket code:

(require math/array)
(define mask_cube
  (let ([leng 5])
    `(make-array #(,leng ,leng) 0)))

What I want it to do, written in python:

np.zeros((5,5))

Why isn't the comma working like I think it should? If there's a more elegant way to solve the problem, please let me know. Mostly I just want my pretty, short np.zeros() function

Moreover, if there's something fundamental I'm misunderstanding about backquote, commas, or racket (or even Lisp in general), please let me know.

You do not want eval here. Rather, you are quoting too much; the simple solution to your problem is to move the ` inwards to the appropriate place:

(define mask_cube
  (let ([leng 5])
    (make-array `#(,leng ,leng) 0)))

However, I’d generally avoid quotation if you’re a beginner; it is more complicated than it needs to be. Just use the vector function instead, which is easier to understand:

(define mask_cube
  (let ([leng 5])
    (make-array (vector leng leng) 0)))

For an in-depth treatment of quotation (with quasiquotation at the end), see What is the difference between quote and list?.