Question

As some of you know I am implementing Shen in Clojure.
Since Shen has a dual namespace and all symbols evaluate to themselves I need a Clojure macro, which binds the symbol to itself and the value to a postfixed symbol.

Now also symbols like *language* have to be bound. But when I use the following macro with *language* as a parameter I get Warning: *language* not declared dynamic and thus is not dynamically rebindable, but its name suggests otherwise. Please either indicate ^:dynamic *language* or change the name.

(defmacro set [x y] 
  `(let [y# ~y]
    (def ^:dynamic ~x '~x)
    (intern *ns* (symbol (str (name ~x) "__varPoF__")))
    (def ^:dynamic ~(symbol (str (name x) "__varPoF__")) y#)
    y#))

Can someone tell me why this is not working?

Answer 1

The use of reader macros is wrong here. You have to use with-meta. I’m also not sure why you need the intern call.

(defmacro set
  [x y]
  (let [dynamic {:dynamic true}]
    `(let [y# ~y]
       (def ~(vary-meta x merge dynamic) '~x)
       (def ~(vary-meta (symbol (str (name x) "__varPoF__")) merge dynamic) y#)
       y#)))

Shameless self-promotion: with-meta and the reader.