On Mon, Nov 3, 2008 at 9:13 AM, Chanwoo Yoo <[EMAIL PROTECTED]> wrote:
>
> Below code is copied from 'On Lisp'. I just changed , to ~. But this
> code does not work in Clojure.
>
> (defmacro abbrev [short long]
> `(defmacro ~short [& args]
> `(~'~long [EMAIL PROTECTED])))
>
> Is there any important issue what I am overlooking when writing macros
> in Clojure? Any help appreciated.
(defmacro abbrev [short long]
`(defmacro ~short [& args#]
`(~'~long [EMAIL PROTECTED])))
Your clue here is the error message:
Can't use qualified name as parameter: user/args
Clojure has a unique combination of features that help increase the
hygine of macros. In your original translation, the word "args" was
resolved into the "user" namespace because it was left bare. For
local names (like formal arguments, "let" locals, etc.) you don't want
that, so you need to use some mechanism to make it clear what you
mean. One such mechanism is gensym (in this case I used the trailing
# which is an auto-gensym). Another option is ~'foo which would
explicitly capture "foo" from the context where the macro is expanded.
--Chouser
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