wtf.ls

memoised-fork = (f, future) ->
  pending = []

  fold = (g, h) ->
    fold := (g, h) -> pending.push rejected: g, resolved: h
    f do
      * (a) -> do
               future.is-pending  := false
               future.is-rejected := true
               future.value       := a
               fold               := (ff, _) -> ff a
               invoke-pending \rejected, a
               g a
      * (b) -> do
               future.is-pending  := false
               future.is-resolved := true
               future.value       := a
               fold               := (_, ff) -> ff b
               invoke-pending \resolved, b
               h b

  return (g, h) -> fold g, h

  function invoke-pending(kind, value)
    for x in pending => x[kind] value