SA-C

/* SA-C (Single-Assignment C): Gaussian 3x3 blur kernel applied to a 2D array */
/* Demonstrates SA-C array comprehensions and reductions */

float[.,.] blur3x3(float[.,.] img) {
    int rows = shape(img, 0);
    int cols = shape(img, 1);

    float[3,3] kernel = [[1.0, 2.0, 1.0],
                          [2.0, 4.0, 2.0],
                          [1.0, 2.0, 1.0]];

    float[rows-2, cols-2] result =
        {| (1.0/16.0) * sum({| kernel[kr,kc] * img[r+kr, c+kc]
                             : kr in [0..3], kc in [0..3] |})
         : r in [0..rows-2], c in [0..cols-2] |};

    return result;
}

float[.] row_sums(float[.,.] m) {
    return {| sum({| m[r,c] : c in [0..shape(m,1)] |})
            : r in [0..shape(m,0)] |};
}