//
// function to decide whether string is a palindrome,
// ignoring case and considering letters only 
//

/*
// function we wrote in class to check whether character is a letter
// probably better to use library function isLetter 
def isLowerCaseLetter(ch : Char) : Boolean = {
  ('a' <= ch) && (ch <= 'z')
}
*/

def isPalindrome(input : String) : Boolean = {
  // val lcLetters = input.toLowerCase.filter(isLowerCaseLetter(_))
  val lcLetters = input.toLowerCase.filter(_.isLetter)
  lcLetters == lcLetters.reverse
}