What's the syntax for creating a byte array in Clojure initialized to a specified collection of values?
Something like this, but that works...
(byte-array [0 1 2 3])
1
-
1your sample does work in later versions of clojure (tested in 1.8). Not sure when it changed.Phil Cooper– Phil Cooper2017-04-11 13:34:11 +00:00Commented Apr 11, 2017 at 13:34
Add a comment
|
4 Answers
(byte-array (map byte [0 1 2 3]))
afaik Clojure has no byte literals.
1 Comment
David J.
Correct; as of Clojure 1.5, it does not have a byte literal: clojure.org/reader
Other posters have given good answers that work well.
This is just in case you are doing this a lot and want a macro to make your syntax a bit tidier:
(defmacro make-byte-array [bytes]
`(byte-array [~@(map (fn[v] (list `byte v)) bytes)]))
(aget (make-byte-array [1 2 3]) 2)
=> 3
1 Comment
David J.
A function would work just as well, right? This answer breaks the first rule of Macro Club: Don't Write Macros!
(byte-array [(byte 0x00) (byte 0x01) (byte 0x02) (byte 0x03)])
Comments
(byte-array [(byte 0) (byte 1) (byte 2)])
Explanation:
byte creates a byte
byte-array creates a byte[]
bytes converts it to byte[]
5 Comments
Maurits Rijk
byte-array creates byte[], so the call to bytes is not needed.
Goran Jovic
You are right. Repl automatically boxing primitives got me confused. Corrected
Michał Marczyk
In fact,
byte coerces to byte, although in 1.2 all arguments to functions are autoboxed, so byte-array still receives Byte-s and needs to unbox them. Try (loop [i (byte 0)] (recur (Byte. 0))) at a 1.2 REPL to verify this.Goran Jovic
Ok, so if I'm testing the type with
(class (byte 1)) it will yield java.lang.Byte because it was boxed when passed to class function, although (byte 1) was a primitive byte.
fooledbyprimes
Is the following garbage? (class (byte-array [(byte 0) (byte 1) (byte 2)])) which gives strange [B in the repl output.