nested-keywords.clj

(name :foo/bar)
(namespace :foo/bar)
(namespace (keyword (name :foo/bar/baz)))

(keyword "foo" "bar/baz")
(keyword "foo" (str (keyword "bar" "baz")))

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(use 'criterium.core)
(quick-bench (namespace :foo/bar))                             ;; 3.566772 ns
(quick-bench (clojure.string/split (str :foo/bar) #"/"))       ;; 169.893638 ns

(quick-bench (namespace (keyword (name :foo/bar/baz))))        ;; 51.160878 ns
(quick-bench (clojure.string/split (str :foo/bar/baz) #"/"))   ;; 211.924696 ns

;; scales linearly
(quick-bench (namespace (keyword (name (keyword (name (keyword (name :foo/bar/baz/qux/quz))))))))   ;; 153.071653 ns
(quick-bench (clojure.string/split (str :foo/bar/baz/qux/quz) #"/"))                                ;; 290.058293 ns

;; slower at 11 levels of nesting
(quick-bench (namespace (keyword (name (keyword (name (keyword (name (keyword (name (keyword (name (keyword (name (keyword (name (keyword (name (keyword (name :foo/bar/baz/qux/quux/quuz/corge/grault/garply/waldo/fred))))))))))))))))))))   ;; 630.593118 ns
(quick-bench (clojure.string/split (str :foo/bar/baz/qux/quux/quuz/corge/grault/garply/waldo/fred) #"/"))     ;; 614.892063 ns

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;; scales linearly
(quick-bench (keyword "foo" "bar"))                                               ;; 18.681389 ns
(quick-bench (keyword "foo" (str (keyword "bar" "baz"))))                         ;; 32.015719 ns
(quick-bench (keyword "foo" (str (keyword "bar" (str (keyword "baz" "qux"))))))   ;; 51.849270 ns

;; vs. str
(quick-bench (keyword "foo" (str (keyword "bar" "baz"))))  ;; 32.015719 ns
(quick-bench (keyword "foo" (str "bar/" "baz")))           ;; 77.870166 ns
(quick-bench (keyword (str "foo/" "bar/" "baz")))          ;; 127.062484 ns