So, in a word: I need a tutorial for dummies
I don't know of any tutorials like you have described. Perhaps someone else does?
Now, my current problem is: my program for solving quadratic equation won't compile...
You left out some 'Just' constructors. import System solve_qe :: Maybe (Double, Double, Double) -> Maybe (Double, Double) solve_qe Nothing = Nothing --solve_qe (a, b, c) solve_qe (Just (a, b, c)) | d >= 0 = Just ((-b + (sqrt d)) / (2 * a), (-b - (sqrt d)) / (2 * a)) | otherwise = Nothing where d = b^2 - 4*a*c evalArgs :: [String] -> Maybe (Double, Double, Double) --evalArgs (a:b:c:[]) = (read a, read b, read c) evalArgs (a:b:c:[]) = Just (read a, read b, read c) evalArgs _ = Nothing main = do args <- getArgs print (solve_qe (evalArgs args))