my code is structured like this , in summary: -- this function will return th N°BD from Sidonie for a given name -- note: names have been standardized between Sidonie and WDS getAlphaDelta :: Connection -> String -> IO (Double,Double) getAlphaDelta conn name = do let qry_head_AlphaDelta_AngularDistance = "select alpha,delta from AngularDistance where Nom = ?" :: Query (alpha_delta_rows :: [(Double,Double)]) <- query conn qry_head_AlphaDelta_AngularDistance (Only (name::String)) -- putStrLn $ show alpha_delta_rows return (head alpha_delta_rows) main = do conn <- connect defaultConnectInfo { connectHost = "moita", connectUser = "mattei", connectPassword = "sidonie2", connectDatabase = "sidonie" } -- check getAlphaDelta works: let name3 = "A 7" putStrLn $ show name3 ad3 <- getAlphaDelta conn name3 putStr "ad3 =" putStrLn $ show ad3 this works i got result such as: "A 7" ad3 =(11297.0,-619.0) if i move the 5 lines of code at the end of file it segfault between the begin and end i have some DB connection and queriung , filtering, mapping... any idea? should i really upgrade the version of GHCI? Damien