Bytes – Jadpo

A Bytes value is a whole: the bytes operations make a new one, encoding writes it as text and reads it back, and hash digests it. Each is called as bytes.<name>. bytes is a reserved name, as every standard namespace is, so a variable that holds bytes is called something else, such as raw or body.

Operation	Gives	Fails	SQL form
`concat(first, second)`	`Bytes`, `first`'s bytes then `second`'s; any value built on `Bytes` goes in, and what comes out is plain `Bytes`		none

Joining works on the bytes themselves, so nothing passes through text. A Merkle tree's node hash, RFC 6962 section 2.1's SHA-256(0x01 || left || right), is two joins. The value in the test is the root of RFC 6962's first two test leaves:

example

type TreeHash = Bytes {}type HexDigits = Text {}type BadHexDigits = Failure {    kind: FailureKind.invalid_value}/// The bytes hexadecimal text holds.function read_tree_hash(hex_text: HexDigits) fails BadHexDigits -> TreeHash {    var raw: Bytes = attempt encoding.from_hex(hex_text) {        malformed: BadHexDigits    }    return TreeHash(raw)}/// A node's hash, from its two children's: a `01` byte says it is a node's.function join_children(left: TreeHash, right: TreeHash) fails BadHexDigits -> TreeHash {    var prefix: TreeHash = attempt read_tree_hash("01")    return TreeHash(hash.sha256(bytes.concat(bytes.concat(prefix, left), right)))}

example

test "two joins make a node's input" {    var left: TreeHash = attempt read_tree_hash(        "6e340b9cffb37a989ca544e6bb780a2c78901d3fb33738768511a30617afa01d"    )    var right: TreeHash = attempt read_tree_hash(        "96a296d224f285c67bee93c30f8a309157f0daa35dc5b87e410b78630a09cfc7"    )    var joined_hash: TreeHash = attempt join_children(left, right)    assert encoding.to_hex(        joined_hash    ) == "fac54203e7cc696cf0dfcb42c92a1d9dbaf70ad9e621f4bd8d98662f00e3c125"    var no_bytes: Bytes = encoding.to_utf8("")    assert encoding.to_hex(bytes.concat(no_bytes, left)) == encoding.to_hex(left)    assert encoding.to_hex(bytes.concat(left, no_bytes)) == encoding.to_hex(left)}