Handling Ctrl-C cleanly in Haskell

module Main where

import System.Posix.Signals (installHandler, Handler(Catch), sigINT, sigTERM)
import Control.Concurrent.MVar (modifyMVar_, newMVar, withMVar, MVar)

import System.ZMQ4

handler :: MVar Int -> IO ()
handler s_interrupted = modifyMVar_ s_interrupted (return . (+1))

main :: IO ()
main = withContext $ \ctx ->
withSocket ctx Rep $ \socket -> do
bind socket "tcp://*:5555"
s_interrupted <- newMVar 0
installHandler sigINT (Catch $ handler s_interrupted) Nothing
installHandler sigTERM (Catch $ handler s_interrupted) Nothing
recvFunction s_interrupted socket

recvFunction :: (Ord a, Num a, Receiver b) => MVar a -> Socket b -> IO ()
recvFunction mi sock = do
receive sock
withMVar mi (\val -> if val > 0
then putStrLn "W: Interrupt Received. Killing Server"
else recvFunction mi sock)