clojure.core/ints

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Type: function Added: Clojure 1.0 Examples: 2 Runnable: 0

([xs])

Casts to int[]

Examples

by tomdl89 on 2022-07-01 . May have evaluation errors. ▶

(def my-floats (float-array [1.1 2.2 3.3]));; => #'user/my-floats ;; int-array will convert where possible (int-array my-floats);; => [1, 2, 3] ;; ints will not (try (ints my-floats) (catch ClassCastException e (ex-message e)));; => "[F cannot be cast to [I"

by tomdl89 on 2023-04-23 . May have evaluation errors. ▶

;; Casting avoids expensive reflection, so to see the benefit, enable warning: (set! *warn-on-reflection* true) ;; We'll def an int-array but won't type-hint the var: (def my-array (int-array [10 20 30 40 50 60])) ;; and try to amap over it without using `ints` or type hinting: (amap my-array i _ (unchecked-inc-int (aget my-array i))) ;; Reflection warning… call to static method alength on clojure.lang.RT can't be resolved (argument types: unknown). ;; Reflection warning… call to static method aclone on clojure.lang.RT can't be resolved (argument types: unknown). ;; Reflection warning… call to static method aget on clojure.lang.RT can't be resolved (argument types: unknown, int). ;; Reflection warning… call to static method aset on clojure.lang.RT can't be resolved (argument types: unknown, int, int). ;; => [11, 21, 31, 41, 51, 61] ;; We can use `ints` to avoid reflection: (amap (ints my-array) i _ (unchecked-inc-int (aget (ints my-array) i))) ;; => [11, 21, 31, 41, 51, 61] ;; Just as we can type hint in place: (amap ^ints my-array i _ (unchecked-inc-int (aget ^ints my-array i))) ;; => [11, 21, 31, 41, 51, 61] ;; Or type hint the var: (def ^"[I" my-array (int-array [10 20 30 40 50 60])) (amap my-array i _ (unchecked-inc-int (aget my-array i))) ;; => [11, 21, 31, 41, 51, 61]

See also

• clojure.core/int-array

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