I'd tend to code this so that the test was the first form, and then
any number of additional remaining forms become the body, in an
implicit do. Obviously, if you're writing something like this, its
for side effects.
In addition, I'd wrap the body in an annonymous function, defined in a
let, so that the code of the body only needs to exists once in the
macro.
This is off the top of my head:
(defmacro dowhile [test & body]
`(let [body# #(~...@body)]
(body#)
(while ~test (body#))))
On Fri, Oct 9, 2009 at 12:56 PM, nilamo <7nil...@gmail.com> wrote:
>
> Hey all. I'm pretty new to Clojure, and wanted to try my hand at
> writing a macro.
>
> 'dowhile' is nothing special, but I'd still like to hear any comments/
> suggestions you may have.
>
> (defmacro dowhile [body test]
> `(do ~body (while ~test ~body)))
>
> A test shows...
> (macroexpand-1 '(dowhile (dosync (alter x inc)) (< @x 5)))
> => (do (dosync (alter x inc)) (clojure.core/while (< (clojure.core/
> deref x) 5) (dosync (alter x inc))))
>
> And to show that it works...
> (def x (ref 0))
> (println @x) ; 0
> (dowhile (dosync (alter x inc)) (< @x 5))
> (println @x) ; 5
>
> (dowhile (dosync (alter x dec)) (> @x 7))
> (println @x) ; 4
>
> Thanks in advance.
>
> >
>
--
Howard M. Lewis Ship
Creator of Apache Tapestry
The source for Tapestry training, mentoring and support. Contact me to
learn how I can get you up and productive in Tapestry fast!
(971) 678-5210
http://howardlewisship.com
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