matmul(A(2), B(2)) [i,j] :=
        let k := 1...size(B);
        in  sum( A[i,k] * B[k,j] );

//Example Use
a := [[1, 2],
      [3, 4]];

b := [[-3, -8, 3],
      [-2,  1, 4]];

test := matmul(a, b);