'input.txt' as src_file

class Queue

    new list  as items
    condition as ready

    define item_put
        items push ready notify

    define item_get
        items empty if ready wait
        items shift

Queue as lines
Queue as count

thread reader
    "file://r:%(src_file)s" open each lines.item_put
    NULL lines.item_put count.item_get "reader: %d\n" print

thread writer
    0 repeat lines.item_get dup while
        "writer: %s" print 1+
    drop count.item_put

reader as r
writer as w