# Curryer - Fast Haskell-to-Haskell RPC
Curryer (pun intended) is a fast, Haskell-exclusive RPC (remote procedure call) library. By using the latest Haskell serialization and streaming libraries, curryer aims to be the fastest and easiest means of communicating between Haskell-based processes.
Curryer is inspired by the now unmaintained [distributed-process](https://hackage.haskell.org/package/distributed-process) library, but is lighter-weight and uses a higher-performance serialization package.
## Features
* blocking and non-blocking remote function calls
* asynchronous server-to-client callbacks (for server-initiated notifications)
* timeouts
* leverages [winery](https://hackage.haskell.org/package/winery) for high-performance serialization
## Requirements
* GHC 8.6+
## Code Example
[Server](https://github.com/agentm/curryer/examples/SimpleKeyValueServer.hs):
```haskell
data SetKey = SetKey String String
deriving (Generic, Show)
deriving Serialise via WineryVariant SetKey
data GetKey = GetKey String
deriving (Generic, Show)
deriving Serialise via WineryVariant GetKey
main :: IO ()
main = do
kvmap <- M.newIO
void $ serve kvRequestHandlers kvmap localHostAddr 8765 Nothing
kvRequestHandlers :: RequestHandlers (M.Map String String)
kvRequestHandlers = [ RequestHandler $ \state (SetKey k v) ->
atomically $ M.insert v k (connectionServerState state)
, RequestHandler $ \state (GetKey k) ->
atomically $ M.lookup k (connectionServerState state)
]
```
[Client](https://github.com/agentm/curryer/examples/SimpleKeyValueClient.hs):
```haskell
data SetKey = SetKey String String
deriving (Generic, Show)
deriving Serialise via WineryVariant SetKey
data GetKey = GetKey String
deriving (Generic, Show)
deriving Serialise via WineryVariant GetKey
data CommandOptions = Get {name :: String}
| Set {name :: String, value :: String}
deriving (Generic, Show)
instance ParseRecord CommandOptions
main :: IO ()
main = do
opts <- getRecord "SimpleKeyValueClient"
conn <- connect [] localHostAddr 8765
case opts of
Get k -> do
eRet <- call conn (GetKey k)
case eRet of
Left err -> error (show err)
Right (Just val) -> putStrLn val
Right Nothing -> error "no such key"
Set k v -> do
eRet <- call conn (SetKey k v)
case eRet of
Left err -> error (show err)
Right () -> pure ()
```