Step by Step solution about How to resolve the algorithm Guess the number/With feedback (player) step by step in the Haskell programming language

Detailed Haskell Source Code Explanation:

Source Code 1:

• main Function:

  • This is the entry point of the program.
  • It prompts the user to enter the range of numbers (from and to).
  • It reads the user input and checks if it's valid using the reads function.
  • If the input is valid, it calls the loop function with the start and end of the range.
  • If the input is invalid, it prints an error message and calls main again to restart the program.

• loop Function:

  • This function takes the start and end of the range as input.
  • It calculates the midpoint (guess) of the range and prints it to the user, asking them if it's the correct value.
  • It reads the user's response and takes appropriate action based on the response:
    • If the guess is correct ("c"), it prints "Awesome!"
    • If the guess is too low ("l"), it calls loop again with the updated range (from the start to the guess).
    • If the guess is too high ("h"), it calls loop again with the updated range (from the guess to the end).
    • If the user's input is invalid, it prints an error message and calls loop again with the same range.

Source Code 2 (Alternative Version):

• main Function:
  • This function is simpler and uses more concise syntax.
  • It sets up a recursive function f with a default range of 0 to 100.
  • The f function computes the midpoint of the range, prints it to the user, and prompts them for input.
  • It then handles the user's response in the same way as the loop function in Source Code 1:
    • If the guess is correct ("c"), it prints "Yay!"
    • If the guess is too low ("l"), it calls f with the updated range (from the start to the midpoint).
    • If the guess is too high ("h"), it calls f with the updated range (from the midpoint to the end).

main :: IO ()
main = do
    putStrLn "Please enter the range:"
    putStr   "From: "
    from <- getLine
    putStr   "To: "
    to   <- getLine
    case (from, to) of
         (_) | [(from', "")] <- reads from
             , [(to'  , "")] <- reads to
             , from'         < to' -> loop from' to' 
         (_)  -> putStrLn "Invalid input." >> main

loop :: Integer -> Integer -> IO ()
loop from to = do
    let guess = (to + from) `div` 2
    putStrLn $ "Is it " ++ show guess ++ "? ((l)ower, (c)orrect, (h)igher)"
    answer <- getLine
    case answer of
        "c" -> putStrLn "Awesome!"
        "l" -> loop from  guess
        "h" -> loop guess to
        (_) -> putStrLn "Invalid answer." >> loop from to


main = f 0 100
  where f x y = let g = div (x + y) 2 in
          putStrLn (show g ++ "? (l,h,c)") >>
          getLine >>= \a -> case a of
                              "l" -> f x g
                              "h" -> f g y
                              "c" -> putStrLn "Yay!"