Comments on: Macros make Elvis better http://blogs.foognostic.net/2009/11/macros-make-elvis-better/ Seeking knowledge of foo Wed, 13 Jan 2010 14:49:16 +0000 hourly 1 http://wordpress.org/?v=3.0.1 By: Seth Schroeder http://blogs.foognostic.net/2009/11/macros-make-elvis-better/comment-page-1/#comment-348 Seth Schroeder Mon, 16 Nov 2009 13:48:34 +0000 http://blogs.foognostic.net/?p=222#comment-348 <p>Apparently so! I hadn't thought about using (or) for some strange reason. It would be a bad (or) that didn't defer evaluation.</p> <p>It was fun trying to combine (or) and (def) with a macro. I'm learning about macros slowly but don't understand why one of these works and the other fails:</p> <p><code lang="clojure"> (defmacro ordef-happy [var t f] `(def ~var (or ~t ~f))) (defmacro ordef-fale [var t f] (def var (or t f))) user> (def foo :UGH) (ordef-happy foo :bar :baz) foo :bar user> (def foo :UGH) (ordef-fale foo :bar :baz) foo :UGH </code></p> Apparently so! I hadn’t thought about using (or) for some strange reason. It would be a bad (or) that didn’t defer evaluation.

It was fun trying to combine (or) and (def) with a macro. I’m learning about macros slowly but don’t understand why one of these works and the other fails:

(defmacro ordef-happy [var t f]
  `(def ~var (or ~t ~f)))

(defmacro ordef-fale [var t f]
  (def var (or t f)))

user> (def foo :UGH) (ordef-happy foo :bar :baz) foo
:bar
user> (def foo :UGH) (ordef-fale foo :bar :baz) foo
:UGH

]]> By: Glen http://blogs.foognostic.net/2009/11/macros-make-elvis-better/comment-page-1/#comment-345 Glen Mon, 16 Nov 2009 07:02:11 +0000 http://blogs.foognostic.net/?p=222#comment-345 <p>Is that just the same as writing:</p> <p>(or (nap 123) (nap 456))</p> <p>?</p> Is that just the same as writing:

(or (nap 123) (nap 456))

?

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