@FILES
  {"fifo"; "The Fifo structure";}
@SIGNATURE FIFO "fifo" {
  @TYPES 
    @TYPE fifo
  @EXCEPTIONS 
    Dequeue
  @VALS 
    foldl
    length
    peek
    foldr
    enqueue
    map
    contents
    app
    head
    delete
    isEmpty
    dequeue
    empty
}
@STRUCTURE Fifo "fifo" FIFO
