X-Git-Url: https://git.distorted.org.uk/~mdw/lisp/blobdiff_plain/b2c12b4eaf6e5c43791d95080a243c35f97ee488..af33e77c00654c222a8a04a5e69a5eb1f56c1e8c:/mdw-base.lisp

diff --git a/mdw-base.lisp b/mdw-base.lisp
index 646eb7e..a41b685 100644
--- a/mdw-base.lisp
+++ b/mdw-base.lisp
@@ -31,7 +31,8 @@
   (:export #:unsigned-fixnum
 	   #:compile-time-defun
 	   #:show
-	   #:stringify #:mappend #:listify #:fix-pair #:pairify
+	   #:stringify #:functionify #:mappend
+	   #:listify #:fix-pair #:pairify
 	   #:parse-body #:with-parsed-body
 	   #:whitespace-char-p
 	   #:slot-uninitialized
@@ -83,6 +84,13 @@
     (symbol (symbol-name str))
     (t (princ-to-string str))))
 
+(defun functionify (func)
+  "Convert the function-designator FUNC to a function."
+  (declare (type (or function symbol) func))
+  (etypecase func
+    (function func)
+    (symbol (symbol-function func))))
+
 (defun mappend (function list &rest more-lists)
   "Apply FUNCTION to corresponding elements of LIST and MORE-LISTS, yielding
    a list.  Return the concatenation of all the resulting lists.  Like
@@ -127,6 +135,17 @@
        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