Problem expanding macro in clojure

Question

I have a clojure macro:

(defmacro show
  [x] `(show-fn ~x)
)

: which given :

(show hello)

I want to resolve to :

(show-fn 'hello)

: How can I do this?

Rayne · Accepted Answer · 2010-12-31 18:30:53Z

3

user=> (defmacro show [x] `(~'show-fn '~x))
#'user/show
user=> (macroexpand '(show hello))
(show-fn (quote hello))

This is called 'symbol capture'. It keeps the symbol from being resolved in the current namespace, as with your example.

edited Dec 31, 2010 at 18:30

answered Dec 31, 2010 at 17:34

Rayne

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3 Comments

Rayne Over a year ago

@Zubair Done. Note that it isn't going to actually expand to 'hello, because ' expands to quote. It's the same thing though.

amalloy Over a year ago

You probably don't want to capture show-fn - it's usually better to let that one be syntax-quoted, like (show-fn '~x).

Rayne Over a year ago

He did for some reason. Not sure if you were responding to him or me. I was just answering the question rather than giving a lecture on why not to do it.

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