Hi The little program below is to test an idea to try to interact using Hugs or GHCi with a running program. To use the program: 1. Start the server with "addServer addChan" 2. Write requests to addChan "writeChan addChan (Add 3 4)" The program seems to work OK in Hugs, but crashes out with "ghc: no threads to run". Can anybody suggest a way of getting this to run properly with GHCi? Thanks Johnny ---- Transcript of a Hugs session: Type :? for help ConcTest> addServer addChan addServer started ConcTest> writeChan addChan (Add 3 4) 1: addServer: 3 + 4 = 7 ---- Transcript of a GHCi session: Loading package concurrent ... linking ... done. Compiling ConcTest ... compilation IS required ConcTest> addServer addChan addServer started ghc: no threads to run: infinite loop or deadlock? bash$ ---- module ConcTest where import Concurrent import IOExts data AddMsg = Add Int Int | Quit addServer :: Chan AddMsg -> IO () addServer c = do putStrLn "addServer started" loop 1 putStrLn "addServer finished" where loop msgNum = do msg <- readChan c case msg of Add x y -> do putStrLn (show msgNum ++ ": addServer: " ++ show x ++ " + " ++ show y ++ " = " ++ show (x + y)) loop (msgNum + 1) Quit -> return () addChan :: Chan AddMsg addChan = unsafePerformIO newChan