clojure.core/shorts

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Type: function Added: Clojure 1.1 Examples: 2 Runnable: 1

([xs])

Casts to shorts[]

Examples

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

;; short-array will convert where possible (short-array [32767 32768 32769]);; => [32767, -32768, -32767] ;; shorts will not (try (shorts [32767 32768 32769]) (catch ClassCastException e (ex-message e))) ;; => "clojure.lang.PersistentVector cannot be cast to [S"

by tomdl89 on 2023-04-23 ▶

;; Casting avoids expensive reflection, so to see the benefit, enable warning: (set! *warn-on-reflection* true) ;; We'll def a short-array but won't type-hint the var: (def my-array (short-array [10 20 30 40 50 60])) ;; and try to amap over it without using `shorts` or type hinting: (amap my-array i _ (unchecked-short (unchecked-inc (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, short). ;; => [11, 21, 31, 41, 51, 61] ;; We can use `shorts` to avoid reflection: (amap (shorts my-array) i _ (unchecked-short (unchecked-inc (aget (shorts my-array) i)))) ;; => [11, 21, 31, 41, 51, 61] ;; Just as we can type hint in place: (amap ^shorts my-array i _ (unchecked-short (unchecked-inc (aget ^shorts my-array i)))) ;; => [11, 21, 31, 41, 51, 61] ;; Or type hint the var: (def ^"[S" my-array (short-array [10 20 30 40 50 60])) (amap my-array i _ (unchecked-short (unchecked-inc (aget my-array i)))) ;; => [11, 21, 31, 41, 51, 61]

See also

• clojure.core/short-array

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