egison-3.2.10: lib/core/string.egi
;;;
;;; String.egi
;;;
(define $insert-between
(lambda [$ws $in]
(foldl (lambda [$s1 $s2] {@s1 in s2}) {(car ws)} (cdr ws))))
(define $palindrome?
(lambda [$str]
(match str string
{[(loop $i [1 $n]
<cons $c_i <snoc ,c_i ...>>
(| <nil> <cons $cm <nil>>))
#t]
[_ #f]})))