Data commit

Task/Happy-numbers/Ol/happy-numbers.ol

@@ -0,0 +1,27 @@
+(define (number->list num)
+   (let loop ((num num) (lst #null))
+      (if (zero? num)
+         lst
+         (loop (quotient num 10) (cons (remainder num 10) lst)))))
+
+(define (** x) (* x x))
+
+(define (happy? num)
+   (let loop ((num num) (seen #null))
+      (cond
+         ((= num 1) #true)
+         ((memv num seen) #false)
+         (else
+            (loop (apply + (map ** (number->list num)))
+                  (cons num seen))))))
+
+(display "happy numbers: ")
+(let loop ((n 1) (count 0))
+   (unless (= count 8)
+      (if (happy? n)
+         then
+            (display n) (display " ")
+            (loop (+ n 1) (+ count 1))
+         else
+            (loop (+ n 1) count))))
+(print)