Kronecker product

func kronecker_product(a, b) {
    a ~X b -> map { _[0] ~X* _[1] }
}

kronecker_product([[1, 2], [3, 4]],
                  [[0, 5], [6, 7]]).each { .say }

say ''
kronecker_product([[0,1,0],  [1,1,1],   [0,1,0]],
                  [[1,1,1,1],[1,0,0,1], [1,1,1,1]]).each { .say }

Output:

[0, 5, 0, 10]
[6, 7, 12, 14]
[0, 15, 0, 20]
[18, 21, 24, 28]

[0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0]
[0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0]
[0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0]
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
[1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1]
[1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
[0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0]
[0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0]
[0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0]