apply_macro.clj: added new (evil) lib

1 files changed, 43 insertions, 0 deletions

diff --git a/src/clojure/contrib/apply_macro.clj b/src/clojure/contrib/apply_macro.clj
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+++ b/src/clojure/contrib/apply_macro.clj
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+;;; apply_macro.clj: make macros behave like functions
+
+;; by Stuart Sierra, http://stuartsierra.com/
+;; January 28, 2009
+
+;; Copyright (c) Stuart Sierra, 2009. All rights reserved.  The use
+;; and distribution terms for this software are covered by the Eclipse
+;; Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
+;; which can be found in the file epl-v10.html at the root of this
+;; distribution.  By using this software in any fashion, you are
+;; agreeing to be bound by the terms of this license.  You must not
+;; remove this notice, or any other, from this software.
+
+
+;; Don't use this.  I mean it.  It's evil.  How evil?  You can't
+;; handle it, that's how evil it is.  That's right.  I did it so you
+;; don't have to, ok?  Look but don't touch.  Use this lib and you'll
+;; go blind.
+
+
+(ns apply-macro)
+
+;; Copied from clojure.core/spread, which is private.
+(defn- spread
+  "Flatten final argument list as in apply."
+  [arglist]
+  (cond
+   (nil? arglist) nil
+   (nil? (rest arglist)) (seq (first arglist))
+   :else (cons (first arglist) (spread (rest arglist)))))
+
+(defmacro apply-macro
+  "This is evil.  Don't ever use it.  It makes a macro behave like a
+  function.  Seriously, how messed up is that?
+
+  Evaluates all args, then uses them as arguments to the macro as with
+  apply.
+
+  (def things [true true false])
+  (apply-macro and things)
+  ;; Expands to:  (and true true false)"
+  [macro & args]
+  (cons macro (spread (map eval args))))