From 6903ec2dd51e394a5c81f8cb5e192ebc445da537 Mon Sep 17 00:00:00 2001
From: Paulo de Tarso Silva Santos <paulo.santos.ismart@gmail.com>
Date: Thu, 28 May 2015 09:06:37 -0300
Subject: [PATCH] Update fol.lisp
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Transformando o algoritmo do "length-form" em uma recursão de cauda.
---
fol.lisp | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/fol.lisp b/fol.lisp
index 7e2a8fd..bc93296 100644
--- a/fol.lisp
+++ b/fol.lisp
@@ -2,11 +2,12 @@
(and (symbolp x)
(equal (char (symbol-name x) 0) #\?)))
-(defun length-form (form)
- (if (> (length form) 0)
+(defun length-form (form &optional (n 0))
+ (if (not (null form))
(if (atom (car form))
(if (member (car form) '(implies and or equiv))
- (+ 1 (length-form (cdr form)))
- (length-form (cdr form)))
- (+ (length-form (car form)) (length-form (cdr form))))
- 0))
+ (length-form (cdr form) (+ n 1))
+ (length-form (cdr form) n))
+ (progn (setf n (+ n (length-form (car form))))
+ (length-form (cdr form) n)))
+ n))