formatPos :: Filename -> Linenumber -> String
formatPos source ln =
    if ln >= 0
    then source ++ ":" ++ show ln ++ " "
    else source ++ " "
formatPos :: Filename -> Linenumber -> String
formatPos source ln =
    if ln >= 0
    then source ++ ":" ++ show ln ++ " "
    else source ++ " "
formatPos source ln =
    if ln >= 0
    then source ++ ":" ++ show ln ++ " "
    else source ++ " "