!import "base" !Local
!import "list" !Local
!import "io"   !Local

-- Cooperative scheduling with yield.
--   yield returns control to the scheduler so other tasks can run.
--
--   Two tasks print alternately because each yields after every line.

--chatter = (name n :
--  bind (putStrLn (append name " says 1")) (_ :
--  bind yield (_ :
--  bind (putStrLn (append name " says 2")) (_ :
--  bind yield (_ :
--  bind (putStrLn (append name " says 3")) (_ :
--  pure n))))))

chatter = name n : bind <|
  putStrLn (append name " says 1") (_ :
  bind yield (_ :
  bind (putStrLn (append name " says 2")) (_ :
  bind yield (_ :
  bind (putStrLn (append name " says 3")) (_ :
  pure n)))))


main = io <|
  bind (fork (chatter "A" "doneA")) (ha :
  bind (fork (chatter "B" "doneB")) (hb :
  bind yield (_ :
  bind (await ha) (a :
  bind (await hb) (b :
  putStrLn (append "Finished: " (append a (append " " b))))))))