If you want to print something out use putStrLn. It will work. On Fri, Dec 14, 2018 at 03:36:03PM +0100, Damien Mattei wrote:
so itried you code,surpringly it compiles but when i launch it the function can not print somethin on screen, i assume it is because function are pure in haskell, nor with putStrln or Debug.trace:
getBD_WDS :: Connection -> String -> IO Float getBD_WDS conn name = do let qry_head = "select DNUM from WDS where DISC = ?" :: Query
bd_rows <- query conn qry_head (Only name)
let lg = Prelude.length bd_rows
-- putStrLn (if lg > 1 then "some" else "one or zero") let tst = trace (if lg > 1 then "some" else "one or zero") (if lg > 1 then "some" else "one or zero")
-- let noBDtxt :: Text let noBDtxt = fromOnly (Prelude.head bd_rows)
-- noBDstr :: String let noBDstr = Text.unpack noBDtxt
-- noBDfp :: Float let noBDfp = read noBDstr
return noBDfp