Data commit

Task/Loops-Increment-loop-index-within-loop-body/Racket/loops-increment-loop-index-within-loop-body.rkt

@@ -0,0 +1,19 @@
+#lang racket
+
+(require math/number-theory)
+
+(define (comma x)
+  (string-join
+   (reverse
+    (for/list ([digit (in-list (reverse (string->list (~a x))))] [i (in-naturals)])
+      (cond
+        [(and (= 0 (modulo i 3)) (> i 0)) (string digit #\,)]
+        [else (string digit)])))
+   ""))
+
+(let loop ([x 42] [cnt 0])
+  (cond
+    [(= cnt 42) (void)]
+    [(prime? x) (printf "~a: ~a\n" (add1 cnt) (comma x))
+                (loop (* 2 x) (add1 cnt))]
+    [else (loop (add1 x) cnt)]))