Examples.hs

module Control.Concurrent.Actor.Examples where

import System.IO
import Control.Concurrent.Actor

-- -----------------------------------------------------------------------------
-- * Spawning new processes

-- | Using @spawn@.
spawn_1 :: IO ()
spawn_1 = do
  hSetBuffering stdout LineBuffering
  child <- spawn $ const $ say $ "  Hi, I'am the child."
  say $ "I was create a child with PID = " ++ show child

-- > spawn_1
-- ThreadId 44:   Hi, I'am the child.
-- ThreadId 43: I was create a child with PID = ThreadId 44

-- | Make an initial argument type.
data Child = Child String Process

-- | Using @actor@.
actor_1 :: IO ()
actor_1 = do
  hSetBuffering stdout LineBuffering
  me <- self
  say $ "Hi, I'am the parrent."
  child <- actor (Child "child" me) $
    \(Child name parent) _ -> do
      say $ "  Hi, I'am the one who was called " ++ name
      say $ "  My parrent's PID = " ++ show parent
  say $ "I was create a child with PID = " ++ show child

-- > actor_1
-- ThreadId 46: Hi, I'am the parrent.
-- ThreadId 47:   Hi, I'am the one who was called child
-- ThreadId 46: I was create a child with PID = ThreadId 47
-- ThreadId 47:   My parrent's PID = ThreadId 46

-- -----------------------------------------------------------------------------
-- * Communicate
    
-- |
-- There is some Erlang code from the \"Learn You Some Erlang\" book:
-- 
-- @
-- dolphin() ->
--   receive
--     do_a_flip ->
--       io:format(\"How about no?~n\");
--     fish ->
--       io:format(\"So long and thanks for all the fish!~n\");
--     _ ->
--       io:format(\"Heh, we're smarter than you humans.~n\")
--   end
-- @
-- 
dolphin :: String -> IO ()
dolphin "do a flip" = say "How about no?"
dolphin "fish"      = say "So long and thanks for all the fish!"
dolphin _           = say "Heh, we're smarter than you humans."

test_dolphin :: IO ()
test_dolphin = do
  hSetBuffering stdout LineBuffering
  dol <- spawn_receive dolphin
  dol ! "do a flip"
  dol ! "fish"
  dol ! "oh, hello dolphin!"
  return ()

-- > test_dolphin
-- ThreadId 58: How about no?
-- ThreadId 58: So long and thanks for all the fish!
-- ThreadId 58: Heh, we're smarter than you humans.

-- XXX can't send messages to ourselves like this:
-- 
-- send_1 = self <! "hello"
-- 
-- send_2 = self <!> self <! "hello"