module Main where

import System.IO

{-
hexDigit :: Int -> String
hexDigit 0  = "0"
hexDigit 1  = "1"
hexDigit 2  = "2"
hexDigit 3  = "3"
hexDigit 4  = "4"
hexDigit 5  = "5"
hexDigit 6  = "6"
hexDigit 7  = "7"
hexDigit 8  = "8"
hexDigit 9  = "9"
hexDigit 10 = "A"
hexDigit 11 = "B"
hexDigit 12 = "C"
hexDigit 13 = "D"
hexDigit 14 = "E"
hexDigit 15 = "F"
-}

{-
int2hex :: Int -> String
int2hex 0 = ""
int2hex i = int2hex (i `div` 16) ++ hexDigit (i `mod` 16)
-}

{-
int2hex :: Int -> String
int2hex i = int2hex' i True
  where
    int2hex' 0 True  = "0"
    int2hex' 0 False = ""
    int2hex' i _     = int2hex' (i `div` 16) False ++ hexDigit (i `mod` 16)
-}

digit r i | r < 37    = if (i < 10)
                          then show i
                          else [(toEnum (i + 55))::Char]
          | otherwise = "(" ++ (show i) ++ ")"

convert :: Int -> Int -> String
convert _ 0 = ""
convert r i = convert r (i `div` r) ++ digit r (i `mod` r)

{-
convert :: Int -> Int -> String
convert r i = convert' r i True
  where
    convert' _ 0 True  = "0"
    convert' _ 0 False = ""
    convert' r i _     = convert' r (i `div` r) False ++ digit r (i `mod` r)
-}

convert' :: Int -> Int -> String
convert' r i = convert_a r i ""
  where
    convert_a _ 0 result = result
    convert_a r i result = convert_a r (i `div` r) (digit r (i `mod` r) ++ result)

int2bin = convert 2
int2oct = convert 8
int2hex = convert 16

main :: IO ()
main = putStr $ convert' 2 14

{-
main :: IO ()
main = do hSetBuffering stdout NoBuffering
          putStr "Input radix (0 for exit): "
          r <- getLine
          if (r == "0")
            then return ()
            else do putStr "Input number to convert: "
                    i <- getLine
                    putStrLn $ show $ convert' (read r) (read i)
                    main
-}