Return the reader-form from SETF expansion.

[jscl.git] / src / numbers.lisp

diff --git a/src/numbers.lisp b/src/numbers.lisp
index 060e657..18d679c 100644 (file)
--- a/src/numbers.lisp
+++ b/src/numbers.lisp
@@ -15,23 +15,36 @@
 
 ;;;; Various numeric functions and constants
 
-;; Basic functions
-(defun * (x y) (* x y))
-(defun / (x y) (/ x y))
-(defun 1+ (x) (+ x 1))
-(defun 1- (x) (- x 1))
+;; TODO: Use MACROLET when it exists
+(defmacro define-variadic-op (operator initial-value)
+  (let ((init-sym   (gensym))
+        (dolist-sym (gensym)))
+    `(defun ,operator (&rest args)
+       (let ((,init-sym ,initial-value))
+         (dolist (,dolist-sym args)
+           (setq ,init-sym (,operator ,init-sym ,dolist-sym)))
+         ,init-sym))))
+
+(define-variadic-op + 0)
+(define-variadic-op * 1)
+
+;; - and / work differently from the above macro.
+;; If only one arg is given, it negates it or takes its reciprocal.
+;; Otherwise all the other args are subtracted from or divided by it.
+;; TODO: Use MACROLET when it exists
+(defmacro define-sub-or-div (operator unary-form)
+  `(defun ,operator (x &rest args)
+     (cond
+       ((null args) ,unary-form)
+       (t (dolist (y args)
+            (setq x (,operator x y)))
+          x))))
 
-(defun + (&rest args)
-  (let ((r 0))
-    (dolist (x args r)
-      (incf r x))))
+(define-sub-or-div - (-   x))
+(define-sub-or-div / (/ 1 x))
 
-(defun - (x &rest others)
-  (if (null others)
-      (- x)
-      (let ((r x))
-        (dolist (y others r)
-          (decf r y)))))
+(defun 1+ (x) (+ x 1))
+(defun 1- (x) (- x 1))
 
 (defun truncate (x &optional (y 1))
   (floor (/ x y)))
@@ -60,6 +73,7 @@
 (defcomparison =) 
 (defcomparison <)
 (defcomparison <=)
+(defcomparison /=)
 
 (defconstant pi 3.141592653589793)