Just another update

Task/Permutations-by-swapping/PicoLisp/permutations-by-swapping.l

@@ -0,0 +1,42 @@
+(let
+   (N 4
+      L
+      (mapcar
+         '((I) (list I 0))
+         (range 1 N) ) )
+   (for I L
+      (printsp (car I)) )
+   (prinl)
+   (while
+      # find the lagest mobile integer
+      (setq
+         X
+         (maxi
+            '((I) (car (get L (car I))))
+            (extract
+               '((I J)
+                  (let? Y
+                     (get
+                        L
+                        ((if (=0 (cadr I)) dec inc) J) )
+                     (when (> (car I) (car Y))
+                        (list J (cadr I)) ) ) )
+               L
+               (range 1 N) ) )
+         Y (get L (car X)) )
+      # swap integer and adjacent int it is looking at
+      (xchg
+         (nth L (car X))
+         (nth
+            L
+            ((if (=0 (cadr X)) dec inc) (car X)) ) )
+      # reverse direction of all ints large than our
+      (for I L
+         (when (< (car Y) (car I))
+            (set (cdr I)
+               (if (=0 (cadr I)) 1 0) ) ) )
+      # print current positions
+      (for I L
+         (printsp (car I)) )
+      (prinl) ) )
+(bye)