Hello Luca, Monday, February 15, 2010, 8:01:11 PM, you wrote: > I've imported in my module: import Control.Concurrent.STM. > My question is: Have I to use -package stm in ghc command line options? either use -package stm or --make. later automatically imports all required packages -- Best regards, Bulat mailto:Bulat.Ziganshin at gmail.com