clojure.core/create-ns

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Type: function Added: Clojure 1.0 Examples: 4 Runnable: 0

([sym])

Create a new namespace named by the symbol if one doesn't already exist, returns it or the already-existing namespace of the same name.

Examples

by belun on 2010-09-20 . May have evaluation errors. ▶

;; This won't work because the symbol my-new-namespace isn't defined yet (create-ns my-new-namespace) java.lang.Exception: Unable to resolve symbol: my-new-namespace in this context (NO_SOURCE_FILE:2) ;; This won't work because create-ns expects a symbol, not a string (create-ns "my-new-namespace") java.lang.ClassCastException: java.lang.String cannot be cast to clojure.lang.Symbol (NO_SOURCE_FILE:0) ;; Here my-new-namespace is quoted and passed literally to create-ns ;; without being looked up. It works as documented. (create-ns 'my-new-namespace) #<Namespace my-new-namespace>

by belun on 2010-09-20 . May have evaluation errors. ▶

;; Let's create a namespace and check for our result ;; the new namespace will be "my-new-namespace" ;; it does not exist yet, so looking for it, finds nothing (find-ns 'my-new-namespace) nil ;; let's create it (create-ns 'my-new-namespace) #<Namespace my-new-namespace> ;; now searching for it again will have a result (find-ns 'my-new-namespace) #<Namespace my-new-namespace>

by belun on 2010-09-22 . May have evaluation errors. ▶

;; You can create a namespace, not switch to it and still work in, by storing it ;; create the namespace (def for-later-use (create-ns 'my-namespace)) #'user/for-later-use ;; assign a value for a variable (intern for-later-use 'my-var "some value") #'my-namespace/my-var ;; notice how the "for-later-use" symbol has been evaluated to the namespace it represents ;; check the new variable my-namespace/my-var "some value" ;; you can also work on a namespace by using the its name ;; (but quoting it) instead of the return of "create-ns" (intern 'my-namespace 'my-var "some other value") #'my-namespace/my-var ;; check the new assignment and see what's changed my-namespace/my-var "some other value"

by vladkotu on 2023-11-27 . May have evaluation errors. ▶

;; create-ns may be used to override *ns* at macroexpansion (in-ns 'user) (defmacro uses-*ns* [kw] (let [spaced (keyword (str (ns-name *ns*)) (name kw))] `(println ~spaced))) (macroexpand '(user/uses-*ns* :kw)) ;;=> (clojure.core/println :user/kw) ;; 'user' namespace reflects current namespace (binding [*ns* (create-ns 'foo.bar)] (macroexpand '(user/uses-*ns* :kw))) ;; => (clojure.core/println :foo.bar/kw) ;; 'user' namespace has been overriden

See also

• clojure.core/remove-ns (0)
• clojure.core/find-ns
• clojure.core/intern (0)

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