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+# Example program showing 'return-continuation-until-mark' return other values
+# alongside continuations.
+#
+# Print out a given list of numbers.
+#
+# To run:
+#   $ git clone https://github.com/akkartik/mu
+#   $ cd mu
+#   $ ./mu continuation4.mu
+#
+# Expected output:
+#   1
+#   2
+#   3
+
+def main [
+  local-scope
+  l:&:list:num <- copy null
+  l <- push 3, l
+  l <- push 2, l
+  l <- push 1, l
+  k:continuation, x:num, done?:bool <- call-with-continuation-mark 100/mark, create-yielder, l
+  {
+    break-if done?
+    $print x 10/newline
+    k, x:num, done?:bool <- call k
+    loop
+  }
+]
+
+def create-yielder l:&:list:num -> n:num, done?:bool [
+  local-scope
+  load-inputs
+  {
+    done? <- equal l, null
+    break-if done?
+    n <- first l
+    l <- rest l
+    return-continuation-until-mark 100/mark, n, done?
+    loop
+  }
+  # A function that returns continuations shouldn't get the opportunity to
+  # return. Calling functions should stop calling its continuation after this
+  # point.
+  return-continuation-until-mark 100/mark, -1, done?
+  assert false, [called too many times, ran out of continuations to return]
+]