Am Montag, 15. September 2008 02:24 schrieb Cetin Sert:
Hi why do I get?
Buffering. For compiled programmes, stdin and stdout are line-buffered by default, so the output doesn't appear until the program finishes. Either put hSetBuffering stdout NoBuffering at the top of main or, better IMO, insert a hFlush stdout into ask before the readLn. And in eval, putStrLn would be better, I think. HTH, Daniel
cetin@linux-d312:~/lab/exp/1> ./eq 23 23 3 a = b = c = n1-0.8457820374040622n2-0.1542179625959377
when I run
import System.IO
main :: IO () main = do a ← ask "a" b ← ask "b" c ← ask "c" eval a b c
ask v = do putStr (v ++ " = ") readLn
eval a b c = do case delta < 0 of True → putStr "neg" False → putStr ("n1" ++ show n1 ++ "n2" ++ show n2) where delta = b*b - 4*c*a n o = (-b `o` sqrt(delta))/(2*a) n1 = n (+) n2 = n (-)