Bytes

bytes are immutable binary data: a b"..." literal, which takes \xNN escapes and no interpolation, or bytes(v) of a string (its UTF-8), an array of integers from 0 to 255, or bytes. b[i] is the integer byte, b.len() the size; + joins and < compares bytes, == by content, and for i, x in b walks them. Bytes are hashable, and print as a literal.

let header = b"\x89PNG";
print(header);           // b"\x89PNG"
print(header[0]);        // 137
print(header.len());     // 4
print(header.hex());     // 89504e47

print(bytes("é"));                // b"\xc3\xa9"
print(bytes([104, 105]));         // b"hi"
print(b"hi" + b"!");              // b"hi!"
print(b"hi" == bytes("hi"));      // true

for i, x in b"hi" {
    print("{i}: {x}");
}
// 0: 104
// 1: 105

A byte cannot be changed; build new bytes instead:

let mut buf = b"ab";
buf[0] = 120; // TypeError: Bytes are immutable.

The bytes namespace

Besides bytes(v) itself, alloc(n[, fill]) (n bytes of fill, default 0), fromHex(s) and fromBase64(s):

print(bytes.alloc(3));             // b"\x00\x00\x00"
print(bytes.alloc(2, 255));        // b"\xff\xff"
print(bytes.fromHex("cafe"));      // b"\xca\xfe"
print(bytes.fromBase64("aGk="));   // b"hi"

Methods

text() (the bytes as UTF-8 text, as a stream’s readText() reads it; anything else is a ValueError), toArray(), slice(start[, end]) (sharing the data), indexOf(sub) (-1 if missing), concat(b, ...), hex() and base64().

let data = b"hello";
print(data.text());                  // hello
print(data.toArray());               // [104, 101, 108, 108, 111]
print(data.slice(1, 3));             // b"el"
print(data.indexOf(b"ll"));          // 2
print(data.concat(b", ", b"world")); // b"hello, world"
print(data.base64());                // aGVsbG8=

print(b"\xff".text()); // ValueError: bytes.text() got bytes that are not valid UTF-8.