fringe

tests/more-tests/fringe.rkt

@@ -0,0 +1,72 @@
+#lang planet dyoo/whalesong/base
+
+;; A tree is either a symbol or a node.
+(define-struct node (l r))
+
+
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define (list-fringe lst success-f fail-f)
+  (cond
+    [(empty? lst)
+     (fail-f)]
+    [else
+     (success-f (first lst)
+                (lambda ()
+                  (list-fringe (rest lst) success-f fail-f)))]))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(define (print-structure generator value)
+  (define (on-success elt restart)
+    (displayln elt)
+    (restart))
+  (define (on-fail)
+    (displayln "Done!"))
+  (generator value on-success on-fail))
+
+
+(define (step-structure generator value)
+  (define (on-success elt restart)
+    (displayln elt)
+    (void (read-line))
+    (restart))
+  (define (on-fail)
+    (displayln "Done!"))
+  (generator value on-success on-fail))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(print-structure list-fringe '(1 2 3 4 5))
+
+  
+
+
+
+
+(define a-tree 
+  (make-node 
+   (make-node 'a (make-node 'b 'c)) 
+   (make-node 'd 'e)))
+
+(define (tree-fringe a-tree success-f fail-f)
+  (cond
+    [(symbol? a-tree)
+     (success-f a-tree fail-f)]
+    
+    [(node? a-tree)
+     (tree-fringe (node-l a-tree)      
+                  success-f
+                  (lambda ()
+                    (tree-fringe (node-r a-tree)
+                                 success-f
+                                 fail-f)))]))
+
+(print-structure tree-fringe 'a)
+(print-structure tree-fringe (make-node 'a 'b))
+(print-structure tree-fringe (make-node (make-node 'a 'b) 'c))
+(print-structure tree-fringe (make-node 'a (make-node 'b 'c)))
+(print-structure tree-fringe (make-node (make-node 'a 'b) (make-node 'c 'd)))
+(print-structure tree-fringe (make-node 'a (make-node 'b (make-node 'c 'd))))
+(print-structure tree-fringe (make-node (make-node (make-node 'a 'b) 'c) 'd))