ANNOUNCE: simple-actors 0.1.0 - an eDSL library for actor model concurrency
I'm happy to announce the release of my library 'simple-actors', a DSL-style library for more structured concurrent programs based on the Actor Model. It offers an alternative to ad-hoc use of Chans that allows for tight control of side-effects and message passing, and is especially suited to applications such as simulations of communicating processes. You can try it with a $ cabal install simple-actors and view the documentation here: http://hackage.haskell.org/package/simple-actors or check out the repo here: https://github.com/jberryman/simple-actors Here is an example of a system of actors working as a binary tree, supporting insert and query operations: ---- EXAMPLE ---- module Main where import Control.Concurrent.Actors import Control.Applicative import Control.Concurrent.MVar type Node = Mailbox Operation -- operations supported by the network: data Operation = Insert { val :: Int } | Query { val :: Int , sigVar :: MVar Bool } -- the actor equivalent of a Nil leaf node: nil :: Behavior Operation nil = Receive $ do (Query _ var) <- received send var False -- signal that Int is not present in tree return nil -- await next message <|> do -- else, Insert received l <- spawn nil -- spawn child nodes r <- spawn nil branch l r . val <$> received -- create branch from inserted val -- a "branch" node with an Int value 'v' and two children branch :: Node -> Node -> Int -> Behavior Operation branch l r v = loop where loop = Receive $ do m <- received case compare (val m) v of LT -> send l m GT -> send r m EQ -> case m of -- signal Int present in tree: (Query _ var) -> send var True _ -> return () return loop insert :: Node -> Int -> IO () insert t = send t . Insert -- MVar is in the 'SplitChan' class so actors can 'send' to it: query :: Node -> Int -> IO Bool query t a = do v <- newEmptyMVar send t (Query a v) takeMVar v main = do t <- spawn nil mapM_ (insert t) [5,3,7,2,4,6,8] mapM (query t) [1,5,0,7] >>= print ---- END EXAMPLE ---- I need to do some work on the documentation and performance testing. If anyone has anyone questions or comments, I would love to hear them. Thanks, Brandon http://coder.bsimmons.name
On Tue, Oct 11, 2011 at 2:37 PM, Brandon Simmons
I'm happy to announce the release of my library 'simple-actors', a DSL-style library for more structured concurrent programs based on the Actor Model. It offers an alternative to ad-hoc use of Chans that allows for tight control of side-effects and message passing, and is especially suited to applications such as simulations of communicating processes.
Pretty interesting!
Here is an example of a system of actors working as a binary tree, supporting insert and query operations: [snip]
I'm kind of spoiled after having used Haskell for a long time, so I couldn't ignore the fact that your example is tied to Ints and don't store a value =). So I've changed the example, as seen below. It's somewhat more complex, but I like the fact that now 'branch' has to deal with updating the value of its key =). -----8<-----BEGIN-EXAMPLE-----8<---- module Main where import Control.Concurrent.Actors import Control.Applicative import Control.Concurrent.MVar type Node k v = Mailbox (Operation k v) -- operations supported by the network: data Operation k v = Insert { key :: k , val :: v } | Query { key :: k , sigVar :: MVar (Maybe v) } -- the actor equivalent of a Nil leaf node: nil :: Ord k => Behavior (Operation k v) nil = Receive $ do (Query _key var) <- received send var Nothing -- signal that key is not present in tree return nil -- await next message <|> do -- else, Insert received l <- spawn nil -- spawn child nodes r <- spawn nil (Insert key val) <- received return $ branch l r key val -- create branch from inserted val -- a "branch" node with a key-value pair and two children branch :: Ord k => Node k v -> Node k v -> k -> v -> Behavior (Operation k v) branch l r k = go where go v = Receive $ do m <- received case compare (key m) k of LT -> send l m >> cont v GT -> send r m >> cont v EQ -> case m of (Query _ var) -> send var (Just v) >> cont v (Insert _ val) -> cont val cont = return . go insert :: Node k v -> (k, v) -> IO () insert t (k,v) = send t (Insert k v) -- MVar is in the 'SplitChan' class so actors can 'send' to it: query :: Node k v -> k -> IO (Maybe v) query t k = do v <- newEmptyMVar send t (Query k v) takeMVar v main :: IO () main = do t <- spawn nil mapM_ (insert t) [(5, "five"), (3, "three"), (7, "seven"), (2, "two"), (4, "four"), (6, "six"), (8, "eight"), (5, "BOO!")] mapM (query t) [1,2,5,7] >>= print -----8<-----END-EXAMPLE-----8<---- Cheers, -- Felipe.
participants (2)
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Brandon Simmons -
Felipe Almeida Lessa