;;;; Various numeric functions and constants
;; 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))))
+
+(define-sub-or-div - (- x))
+(define-sub-or-div / (/ 1 x))
+
+(defun 1+ (x) (+ x 1))
+(defun 1- (x) (- x 1))
+
+(defun truncate (x &optional (y 1))
+ (floor (/ x y)))
+
+(defun integerp (x)
+ (and (numberp x) (= (floor x) x)))
+
+(defun floatp (x)
+ (and (numberp x) (not (integerp x))))
+
+(defun minusp (x) (< x 0))
+(defun zerop (x) (= x 0))
+(defun plusp (x) (< 0 x))
+
+;; TODO: Use MACROLET when it exists
(defmacro defcomparison (operator)
`(defun ,operator (x &rest args)
- (while (not (null args))
- (if (,operator x (car args))
- (setq x (car args)
- args (cdr args))
+ (dolist (y args)
+ (if (,operator x y)
+ (setq x (car args))
(return-from ,operator nil)))
t))
(defcomparison >)
(defcomparison >=)
+(defcomparison =)
(defcomparison <)
(defcomparison <=)
+(defcomparison /=)
(defconstant pi 3.141592653589793)
(defun oddp (x) (not (evenp x)))
(flet ((%max-min (x xs func)
- (while (not (null xs))
- (setq x (if (funcall func x (car xs))
- x
- (car xs))
- xs (cdr xs)))
+ (dolist (y xs)
+ (setq x (if (funcall func x (car xs)) x y)))
x))
(defun max (x &rest xs) (%max-min x xs #'>))
(defun min (x &rest xs) (%max-min x xs #'<)))