Define my own reader macro in clojure

Question

I would like to define my own reader macro in clojure:

(read-string \"ßfoo\")
=> (some_func :foo)

Is it possible?

Answer 1

It is possible to create tagged literals by having a reader map in data_readers.clj at the top of your classpath.

This must be in data_readers.clj at the top of your classpath (usually src directory).

{ß reader-demo.core/read-fn}

This goes into reader-demo.core

(defn some-func
  [arg]
  (str "some-func invoked with " arg))

(defn read-fn
  [arg]
  (-> arg
      keyword
      some-func))

Invoking

#ß foo

will return

"some-func invoked with :foo"

This technique is described here: The reader: Tagged literals

Notice that in practice you should namespace your tagged literals as all non-namespaced ones are reserved for Clojure itself.

Answer 2

Currently, Clojure doesn't allow to create user defined reader macros. This might/might not change in the future.