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(defpackage #:lt-examples
(:use #:cl #:lambda-tools))
(enable-partial-eval-reader-macro)
;; http://rosettacode.org/wiki/Luhn_test_of_credit_card_numbers
(defun luhn (n)
(>> n #'reverse
#$(map 'list #'digit-char-p $char)
#$(mapcar #'*
(loop :for i :upto (length $digits) :collect (1+ (mod i 2)))
$digits)
#$(mapcar #$$(if (> $$x 9) (- $$x 9) $$x) $digits) ;; <-- nested partial eval
#$(zerop (mod (apply #'+ $digits) 10))))
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