Why does `dir` not work with current namespace gotten from "current namespace var" - `*ns*`

user_4835578 0
Viewed 55

Or, in other words, why does this not work:

user=> (dir (ns-name *ns*))
Execution error (ClassCastException) at user/eval2010 (REPL:1).
class clojure.lang.PersistentList cannot be cast to class clojure.lang.Symbol (clojure.lang.PersistentList and clojure.lang.Symbol are in unnamed module of loader 'bootstrap')
clojure
1 Answers

dir is a macro that expects an unquoted symbol as its argument. It should be used like:


user=> (clojure.repl/dir clojure.string)
blank?
capitalize
escape
join
lower-case
replace
...

When you call it like so:

(ns demo.core
  (:require [clojure.repl :as repl]))

(println (repl/dir (ns-name *ns*)))

you are not passing an unquoted symbol (eg clojure.string), but rather a list with the symbol ns-name as its first element.

As the namespace for clojure.repl/dir implies, this command is intended to by typed into a REPL by hand, not used programatically.

If you do want to get information programatically, you probably want something more like one of these:

(ns-publics 'tst.demo.core)
(ns-publics (ns-name *ns*))

either of which works.

Be sure to peruse the Clojure CheatSheet and this list of documentation.

user_18223790
Related