Add (net ricketyspace sicp two thirtyfive).

1 files changed, 32 insertions, 0 deletions

diff --git a/net/ricketyspace/sicp/two/thirtyfive.scm b/net/ricketyspace/sicp/two/thirtyfive.scm
new file mode 100644
index 0000000..a7b4bbe
--- /dev/null
+++ b/net/ricketyspace/sicp/two/thirtyfive.scm
@@ -0,0 +1,32 @@
+;;;; License: CC0-1.0
+
+(define-module (net ricketyspace sicp two thirtyfive)
+  #:export (count-leaves-acc))
+
+
+(define (accumulate op initial sequence)
+  (if (null? sequence)
+      initial
+      (op (car sequence)
+          (accumulate op initial (cdr sequence)))))
+
+
+(define (count-leaves-acc t)
+  (accumulate + 0
+              (map (lambda (p)
+                     (cond ((pair? p)
+                            (count-leaves-acc p))
+                           (else 1)))
+                   t)))
+
+;;; Guile REPL
+;;;
+;;; scheme@(guile-user)> ,use (net ricketyspace sicp two thirtyfive)
+;;; scheme@(guile-user)> (count-leaves-acc '(1 3 (5 7) 9))
+;;; $11 = 5
+;;; scheme@(guile-user)> (count-leaves-acc '((7)))
+;;; $12 = 1
+;;; scheme@(guile-user)> (count-leaves-acc '(1 (2 (3 (4 (5 (6 7)))))))
+;;; $13 = 7
+;;; scheme@(guile-user)>
+