4

I read the following line in this Clojure tutorial - http://java.ociweb.com/mark/clojure/article.html#Macros

'Since macros don't evaluate their arguments, unquoted function names can be passed to them and calls to the functions with arguments can be constructed. Function definitions cannot do this and instead must be passed anonymous functions that wrap calls to functions.'

If it is correct, then why does this work since the function cube is not anonymous-

(defn something [fn x]
  (fn x))

(defn cube [x]
  (* x x x))

(something cube 4)
Improve this question
1
  • You're passing the function cube to something, not just its name. Commented Apr 20, 2011 at 10:00

2 Answers 2

Reset to default
3

You're right, that quote doesn't seem to be correct. I think what it's trying to say is that you cannot pass something that looks like a function call to a function unquoted:

(some-function (bla 1 2 3))

In this case, (bla 1 2 3) will be evaluated as a function call and the return value will be passed to some-function.

(some-macro (bla 1 2 3))

In the case of a macro, what is passed is the list (bla 1 2 3), which can then be used to construct a new function call by inserting arguments, or do something else.

You can definitely still pass a function to another function as you showed, and that's a completely documented and expected technique to use.

Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

-1

defn is s macro, the code is expanded to, since you need the anonymous function: (def something (fn [fn x] (fn x))). I think that what's he is referring to.

Improve this answer

Comments

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.