Foreign.Erlang

Speaks the Erlang network protocol and impersonates an Erlang node on the network. Fully capable of bi-directional communication with Erlang. Erlang types are, as far as reasonable, mapped to Haskell types. Messages to Erlang are just function calls in Haskell, and messages from Erlang are delivered to MVars.

Low-level communication with the Erlang Port-Mapper Daemon

epmdGetNames :: IO [String]

Return the names and addresses of registered local Erlang nodes.

epmdGetPort :: Node -> IO Int

Return the port address of a named Erlang node.

epmdGetPortR4 :: String -> String -> IO (Int, Int, Int, Int, Int, String, String)

Returns (port, nodeType, protocol, vsnMax, vsnMin, name, extra)

type ErlRecv = IO (Maybe ErlType, Maybe ErlType)

type ErlSend = (Maybe ErlType, Maybe ErlType) -> IO ()

Representation of Erlang nodes

type Name = String

Name of an Erlang node.

type Ip = String

Ip address of a remote Erlang node.

data Node

Representation of an Erlang node on the network.

Constructors

Short Name

Local Erlang node.

Long Name Ip

Remote Erlang node.

Instances

Eq Node

Show Node

Erlang Node

erlConnect :: String -> Node -> IO (ErlSend, ErlRecv)

toNetwork :: Int -> Integer -> [Word8]

High-level communication

genCall :: Erlang a => MBox -> Node -> Pid -> a -> IO ErlType

gen_server:call(Pid, Msg)

genCast :: Erlang a => MBox -> Node -> Pid -> a -> IO ()

gen_server:cast(Pid, Msg)

rpcCall :: MBox -> Node -> String -> String -> [ErlType] -> IO ErlType

rpc:call(Node, Module, Function, Arguments)

rpcCast :: MBox -> Node -> String -> String -> [ErlType] -> IO ()

rpc:cast(Node, Module, Function, Arguments)

Mnesia database methods

backup :: MBox -> Node -> String -> IO ErlType

dirtyAllKeys :: MBox -> Node -> String -> IO ErlType

dirtyFirst :: MBox -> Node -> String -> IO ErlType

dirtyNext :: MBox -> Node -> String -> ErlType -> IO ErlType

dirtyLast :: MBox -> Node -> String -> IO ErlType

dirtyPrev :: MBox -> Node -> String -> ErlType -> IO ErlType

dirtyMatchObject :: MBox -> Node -> ErlType -> IO ErlType

dirtyRead :: MBox -> Node -> String -> ErlType -> IO ErlType

dirtySelect :: MBox -> Node -> String -> ErlType -> IO ErlType

Low-level communication

Representation of a Haskell node (program)

data Self

Represents a Haskell node. There should be one of these per process.

createSelf :: String -> IO Self

Instantiate a Haskell node. This initializes the FFI.

Representation of a Haskell process (thread)

data MBox

Haskell threads don't natively have Erlang process IDs. Instead, we use a mailbox abstraction that we can assign PIDs to for communication with Erlang.

createMBox :: Self -> IO MBox

Create a new process on the Haskell side. Usually corresponds to a thread but doesn't need to.

mboxRef :: MBox -> IO ErlType

Return a new unique object reference.

mboxSelf :: MBox -> ErlType

Return the PID of the given mailbox.

Representation of Erlang nodes and processes

type Pid = Either ErlType String

Represents a foreign (Erlang) process. A process can be identified either by its low-level ID (Left pid) or by its registered name (Right name).

Communication to and from Erlang

mboxRecv :: MBox -> IO ErlType

Receive the next message addressed to this mailbox.

mboxRecv' :: MBox -> ErlType -> IO ErlType

Receive a reply message. That is, looks for the next message identified by the given reference.

mboxSend :: Erlang a => MBox -> Node -> Pid -> a -> IO ()

Send an arbitrary message to the specified node and process. In Erlang equivalent to

{Node, Pid} ! Msg.

Native Erlang data types

data ErlType

Constructors

ErlNull

ErlInt Int

ErlBigInt Integer

ErlString String

ErlAtom String

ErlBinary [Word8]

ErlList [ErlType]

ErlTuple [ErlType]

ErlPid ErlType Int Int Int

ErlPort ErlType Int Int

ErlRef ErlType Int Int

ErlNewRef ErlType Int [Word8]

Instances

Eq ErlType

Show ErlType

Binary ErlType

Erlang ErlType

Erlang [ErlType]

Conversion between native Haskell types and ErlType

class Erlang a where

Methods

toErlang :: a -> ErlType

fromErlang :: ErlType -> a

Instances

Erlang Bool

Erlang Int

Erlang Integer

Erlang String

Erlang ErlType

Erlang Node

Erlang a => Erlang [a]

Erlang [ErlType]

(Erlang a, Erlang b) => Erlang (a, b)

(Erlang a, Erlang b, Erlang c) => Erlang (a, b, c)

(Erlang a, Erlang b, Erlang c, Erlang d) => Erlang (a, b, c, d)

(Erlang a, Erlang b, Erlang c, Erlang d, Erlang e) => Erlang (a, b, c, d, e)

Easy type-safe access to tuple members

nth :: Erlang a => Int -> ErlType -> a

Internal packing functions

getA :: Int -> Get String

getC :: Get Int

getErl :: Get ErlType

getN :: Get Int

geta :: Int -> Get [Word8]

getn :: Get Int

putA :: String -> Builder

putC :: Integral a => a -> Builder

putErl :: ErlType -> Builder

putN :: Integral a => a -> Builder

puta :: [Word8] -> Builder

putn :: Integral a => a -> Builder

tag :: Char -> Builder

Miscellaneous utilities

erlangTimeToSeconds :: Integral a => ErlType -> a

Convert a tuple (from erlang:now()) to seconds from Jan 1, 1970.

secondsToErlangTime :: Integral a => a -> ErlType

Convert seconds to an Erlang tuple representing time.