Good Haskell coding style of if/else control block?

Question

I\'m learning Haskell in the hope that it will help me get closer to functional programming. Previously, I\'ve mostly used languages with C-like syntax, like C, Java, and D.

Answer 1

You can use the "case"-construct:

doGuessing num = do
    putStrLn "Enter your guess:"
    guess <- getLine
    case (read guess) of
        g | g < num -> do 
            putStrLn "Too low!"
            doGuessing num
        g | g > num -> do 
            putStrLn "Too high!"
            doGuessing num
        otherwise -> do 
            putStrLn "You Win!"

Answer 2

A minor improvement to mattiast's case statement (I'd edit, but I lack the karma) is to use the compare function, which returns one of three values, LT, GT, or EQ:

doGuessing num = do
   putStrLn "Enter your guess:"
   guess <- getLine
   case (read guess) `compare` num of
     LT -> do putStrLn "Too low!"
              doGuessing num
     GT -> do putStrLn "Too high!"
              doGuessing num
     EQ -> putStrLn "You Win!"

I really like these Haskell questions, and I'd encourage others to post more. Often you feel like there's got to be a better way to express what you're thinking, but Haskell is initially so foreign that nothing will come to mind.

Bonus question for the Haskell journyman: what's the type of doGuessing?