Clojure #= reader macro

Question

I just "discovered" the #= reader macro from a post on Stackoverflow and it solves a problem. How likely is this reader macro to become an official (documented) part of the language? How about deprecated or changed behavior?

The #= reader macro causes the following s-expression to be evaluated by the Lisp reader (before macro expansion).

score 5 · Accepted Answer · answered Jun 21 '11 at 20:27

5

It is used by the core language when something is printed with *print-dup* true, so I'd wager that it is going to stay. No idea why it is not documented.

user=> (binding [*print-dup* true] (prn {:foo 1 :bar 2}))
#=(clojure.lang.PersistentArrayMap/create {:foo 1, :bar 2})
nil

answered Jun 21 '11 at 20:27

Jouni K. Seppänen

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Thanks. I also wonder why it's not documented. It would be useful in macros to evaluate a sub-expression before the macro expands. – Ralph Jun 21 '11 at 20:52

score 3 · Answer 2 · answered Feb 03 '12 at 14:05

3

It's not documented because it could go away / be replaced with something else. I wouldn't recommend using it in your programs.

answered Feb 03 '12 at 14:05

solussd

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Clojure #= reader macro

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