for-each

Calls a function for each element in the argument collection.

When the "for-each" ends, f.ret is pointing back to the argument collection.

set l []
for-each [ 0 1 2 3 4 5 6 7 ]
  def x
    pushr l (2 * x) if x % 2 == 0

the var l will yield [ 0, 4, 8, 12 ] after the for-each the field ret will yield [ 0, 1, 2, 3, 4, 5, 6, 7 ].

set r []
for-each { a: 'A', b: 'B', c: 'C' }
  def k v i l  # key, val, idx, len
    pushr r (+ k v (+ i 1) '/' l)

the var r will yield [ 'aA1/3', 'bB2/3', 'cC3/3' ] after the for-each the field ret will yield { 'a': 'A', 'b': 'B', 'c': 'C' }.

iterating and functions

Iterating functions accept 0 to 3 arguments when iterating over an array and 0 to 4 arguments when iterating over an object.

Those arguments are [ value, index, length ] for arrays. They are [ key, value, index, length ] for objects.

The corresponding key, val, idx and len variables are also set in the closure for the function call.