Initial data commit

Task/Rep-string/EchoLisp/rep-string-1.l

@@ -0,0 +1,17 @@
+(lib 'list) ;; list-rotate
+
+;; a list is a rep-list if equal? to itself after a rotation of lam units
+;; lam <= list length / 2
+;; truncate to a multiple of lam before rotating
+;; try cycles in decreasing lam order (longest wins)
+
+(define (cyclic? cyclic)
+    (define len (length cyclic))
+    (define trunc null)
+
+    (if (> len 1)
+        (for ((lam (in-range (quotient len 2) 0 -1)))
+        (set! trunc (take cyclic (- len (modulo len lam))))
+         #:break (equal? trunc  (list-rotate trunc lam)) => (list->string (take cyclic lam))
+         'no-rep )
+   'too-short-no-rep))