"Debugging tool: print the expression X and its values."
(let ((tmp (gensym)))
`(let ((,tmp (multiple-value-list ,x)))
- (format t "~&")
+ (fresh-line)
(pprint-logical-block (*standard-output* nil :per-line-prefix ";; ")
(format t
"~S = ~@_~:I~:[#<no values>~;~:*~{~S~^ ~_~}~]"
t)
(t nil)))
+(defmacro defconstant* (name value &key doc test)
+ "Define a constant, like `defconstant'. The TEST is an equality test used
+ to decide whether to override the current definition, if any."
+ (let ((temp (gensym)))
+ `(eval-when (:compile-toplevel :load-toplevel :execute)
+ (let ((,temp ,value))
+ (unless (and (boundp ',name)
+ (funcall ,(or test ''eql) (symbol-value ',name) ,temp))
+ (defconstant ,name ,value ,@(and doc (list doc))))
+ ',name))))
+
(declaim (ftype (function nil ()) slot-unitialized))
(defun slot-uninitialized ()
"A function which signals an error. Can be used as an initializer form in