memcache-haskell- Memcache procotol library

MaintainerKiyoshi Ikehara <>
Safe HaskellNone



memcache-haskell is a memcache protocol library for server and client application.

If you want to implement a simple memcache client, just import Network.Memcache module and use withClient function.

import Network.Memcache
main = do
  mValue <- withClient "" $ \client -> get client "key"
  case mValue of
    Nothing -> putStrLn "(no value)"
    Just value -> putStrLn value

Or, use openClient and closeClient pair for more complex cases.

import Control.Exception
import Control.Monad.Trans.Resource (allocate, release, runResourceT)
import Control.Monad.IO.Class
import Network.Memcache
import System.Environment

main :: IO ()
main = do
  args <- getArgs
  case args of
    [] -> main' ""
    (nk:_) -> main' nk

main' :: Nodekey -> IO ()
main' nodekey = runResourceT $ do
  (rkeyClient , client) <- flip allocate closeClient $ do
    c <- openClient nodekey
    case c of
      Just client -> return (client)
      Nothing -> liftIO $ do
        throwIO (userError "could not open.")
  liftIO $ do
    ret <- set client "key" "foo"
    print ret
    ret' <- get client "key" :: IO (Maybe String)
    print ret'
  release rkeyClient

If your application is more complex and should recognize memcache command and response directly, you have to import more and use low-level functions.

For server application, please use Network.Memcache.Op and Network.Memcache.Response directly to parse and process each command.

If you are familiar with conduit library, please take a look at memcache-conduit library and you will find that you can write a memcache protocol server very quickly.

main :: IO ()
main = do
  runResourceT $ do
    runTCPServer (serverSettings 13301 HostAny) $ \appData -> do
      (appSource appData)
        $$ getOpText
        =$ process htVar
        =$ putResponseText
        =$ (appSink appData)

process = ...