Why is clojure adding namespace qualifiers to names inside a backquote?

Question

I am trying to build datalog queries programmatically, but keep running into the problem that I will illustrate with an example function:

(defn test-expr [attribute]
  `[?entity ~attribute ?value]])

When I run (test-expr 3), I would expect the output:

 [?entity 3 ?value]

But instead, I get

[mynamespace/?entity 3 mynamespace/?value]

Which obviously is not what I want. Is there a way to tell clojure "please just quote the list and expand variables I tell you to?"

As to the reason why, it's to prevent users (cough you) from accidentally breaking your macros by defining functions and/or variables with the same name you're using. — Cubic
@Cubic, agreed. As far as I understand, this is some kind of compromise between Scheme hygienic macros and Common Lisp plain macro systems: macro definitions look nearly exactly like Common Lisp ones (this is good, since Scheme macros are harder to write IMO), but by default there is certain level of hygiene present - symbols are not captured blindly but are prefixed with namespace instead. And it is always possible to fall back to plain substitutions when needed (e.g. for anaphoric macros). — Vladimir Matveev

Vladimir Matveev Vladimir Matveev · Accepted Answer · 2012-12-07T07:43:11

Yes, there is.

(defn test-expr [attribute]
  `[~'?entity ~attribute ~'?value])

Here you first unquote the syntax quotation and then immediately quote the symbol (~' construct) again. The result is namespace-less symbol.

It is equivalent to the following, which explains how it works:

(defn test-expr [attribute]
  `[~(quote ?entity) ~attribute ~(quote ?value)])