gistfile1.moon

-- Iterate through each item in each array table passed to iterator
-- doesn't have any allocations

all_values = do
  y = coroutine.yield
  free_workers = setmetatable {}, __mode: "k"

  process_head = (skip, first, ...) ->
    y nil if skip
    return if first == nil
    for item in *first
      y item

    process_head false, ...

  main = (worker) ->
    while true
      process_head true, y nil
      free_workers[worker] = true

  get_free = ->
    if worker = next free_workers
      free_workers[worker] = nil
      worker
    else
      worker = coroutine.wrap main
      worker worker
      worker

  (...) ->
    iter = get_free!
    iter ...
    iter


-- usage:
list1 = {1,2,3,4}
list2 = {5,6,7,8}
list3 = {9,10,11,12}
for item in all_values list1, list2, list3
  print item

-- prints 1,2,3,4,5,6,7,8,9,10,11,12