#!/usr/bin/runghc

module Recursion06IsPalindrome where

import Data.List as L
import Data.Vector as V

isPalindromeRev :: (Eq a) => [a] -> Bool
isPalindromeRev xs = xs == L.reverse xs

isPalindromeRec :: (Eq a, Show a) => Vector a -> Bool
isPalindromeRec xs =
  V.length xs == 1
    || let lastPos = (V.length xs - 1)
           firstElem = xs V.! 0
           lastElem = xs V.! lastPos
        in firstElem == lastElem && isPalindromeRec (V.slice 1 (lastPos - 1) xs)

main :: IO ()
main = do
  print (isPalindromeRev "a")
  print (isPalindromeRev "racecar")
  print (isPalindromeRev "racecat")
  print (isPalindromeRec (V.fromList "a"))
  print (isPalindromeRec (V.fromList "racecar"))
  print (isPalindromeRec (V.fromList "racecat"))