chickadee » generalized-arrays » array-update!

Updates the element in the array at idx as if applying proc to it.

 
(import generalized-arrays
        test)

(define a
  (make-array-from-storage
    vector-storage-class
    (vector 3 3)
    (vector 1 2 3
            4 5 6
            7 8 9)))

(test "Element at #(1 1) is equal to 5"
      5
      (array-ref a #(1 1)))

(array-update!
  a
  #(1 1)
  (lambda (elem) (- elem 20)))

(test "Element at #(1 1) is now equal to -15"
      -15
      (array-ref a #(1 1)))