REVAPPEND, NTHCDR and rewrite some functions without recursion

[jscl.git] / ecmalisp.lisp

diff --git a/ecmalisp.lisp b/ecmalisp.lisp
index 1754c19..c512603 100644 (file)
--- a/ecmalisp.lisp
+++ b/ecmalisp.lisp
@@ -263,13 +263,14 @@
   (defun append (&rest lists)
     (!reduce #'append-two lists '()))
 
   (defun append (&rest lists)
     (!reduce #'append-two lists '()))
 

-  (defun reverse-aux (list acc)
-    (if (null list)
-        acc
-        (reverse-aux (cdr list) (cons (car list) acc))))
+  (defun revappend (list1 list2)
+    (while list1
+      (push (car list1) list2)
+      (setq list1 (cdr list1)))
+    list2)

 
   (defun reverse (list)
 
   (defun reverse (list)

-    (reverse-aux list '()))
+    (revappend list '()))

 
   (defun list-length (list)
     (let ((l 0))
 
   (defun list-length (list)
     (let ((l 0))

@@ -310,29 +311,29 @@
   (defun listp (x)
     (or (consp x) (null x)))
 
   (defun listp (x)
     (or (consp x) (null x)))
 

+  (defun nthcdr (n list)
+    (while (and (plusp n) list)
+      (setq n (1- n))
+      (setq list (cdr list)))
+    list)
+

   (defun nth (n list)
   (defun nth (n list)

-    (cond
-      ((null list) list)
-      ((zerop n) (car list))
-      (t (nth (1- n) (cdr list)))))
+    (car (nthcdr n list)))

 
   (defun last (x)
 
   (defun last (x)

-    (if (consp (cdr x))
-        (last (cdr x))
-        x))
+    (while (consp (cdr x))
+      (setq x (cdr x)))
+    x)

 
   (defun butlast (x)
     (and (consp (cdr x))
          (cons (car x) (butlast (cdr x)))))
 
   (defun member (x list)
 
   (defun butlast (x)
     (and (consp (cdr x))
          (cons (car x) (butlast (cdr x)))))
 
   (defun member (x list)

-    (cond
-      ((null list)
-       nil)
-      ((eql x (car list))
-       list)
-      (t
-       (member x (cdr list)))))
+    (while list
+      (when (eql x (car list))
+        (return list))
+      (setq list (cdr list))))

 
   (defun remove (x list)
     (cond
 
   (defun remove (x list)
     (cond