https://github.com/akkartik/mu/blob/master/continuation4.mu

     1 # Example program showing 'return-continuation-until-mark' return other values
     2 # alongside continuations.
     3 #
     4 # Print out a given list of numbers.
     5 #
     6 # To run:
     7 #   $ git clone https://github.com/akkartik/mu
     8 #   $ cd mu
     9 #   $ ./mu continuation4.mu
    10 #
    11 # Expected output:
    12 #   1
    13 #   2
    14 #   3
    15
    16 def main [
    17   local-scope
    18   l:&:list:num <- copy null
    19   l <- push 3, l
    20   l <- push 2, l
    21   l <- push 1, l
    22   k:continuation, x:num, done?:bool <- call-with-continuation-mark 100/mark, create-yielder, l
    23   {
    24     break-if done?
    25     $print x 10/newline
    26     k, x:num, done?:bool <- call k
    27     loop
    28   }
    29 ]
    30
    31 def create-yielder l:&:list:num -> n:num, done?:bool [
    32   local-scope
    33   load-inputs
    34   {
    35     done? <- equal l, null
    36     break-if done?
    37     n <- first l
    38     l <- rest l
    39     return-continuation-until-mark 100/mark, n, done?
    40     loop
    41   }
    42   # A function that returns continuations shouldn't get the opportunity to
    43   # return. Calling functions should stop calling its continuation after this
    44   # point.
    45   return-continuation-until-mark 100/mark, -1, done?
    46   assert false, [called too many times, ran out of continuations to return]
    47 ]