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(define-module (palindrome))
(define-public (pp str)
"Pretty-printer wrapper for
palindrome?"
(format #f "String ~a is ~aa palindrome!\n"
str
(if (palindrome? str)
"" "not ")))
(define-public (palindrome? str)
"Returns #t if STR is a palindrome, false
otherwise. Ignores casing and non-alphabetic
characters."
(let ((clean (cleanup str)))
(equal? clean (string-reverse clean))))
(define (cleanup str)
(string-downcase (string-filter
char-set:letter str)))
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