Standard library

Standard-library namespaces are imported with use valk.name. Core types such as String, Array, Map, and ByteBuffer are available without importing a separate module in ordinary programs.

Find the right module#

The API reference lists public declarations and signatures. These guides explain common workflows; use the reference when you need the full set of options on a particular type.

Work with a UTC date#

use valk.time

fn main() {
    let date = time.DateTime.new(2026, 1, 15, 9, 30, 0, 0) ! {
        println("Invalid date")
        return
    }
    let tomorrow = date.add_days(1) ! {
        println("Date is outside the supported range")
        return
    }
    println(date.format("Y-m-d"))     // 2026-01-15
    println(tomorrow.format("Y-m-d")) // 2026-01-16
}

DateTime uses UTC. add_* and with_* methods return a new date; methods beginning with modify_ change the existing object. Invalid dates produce an error. DateTime.now() returns the current time, and to_iso8601() produces an ISO-formatted string.

For elapsed durations, use a monotonic clock such as time.mono_ms() instead of comparing wall-clock dates. A monotonic clock is intended for measuring elapsed time even when the system's wall clock changes.

Hash text#

use valk.crypto

fn main() {
    let digest = crypto.sha256_encode("Valk")
    println(digest)
}

sha256_encode produces a hexadecimal SHA-256 digest. Use the operation appropriate to the data: a fast content hash is different from password hashing, for which the library provides bcrypt_hash and bcrypt_verify. crypto.random_bytes(length) supplies random bytes for applications that need them.

Build output in memory#

ByteBuffer is useful when producing text or bytes in several steps:

fn main() {
    let output = ByteBuffer.new()
    output.write("Total: ")
    output.write_f64_ascii(12.5, 2)
    println(output.to_string()) // Total: 12.50
}

Use text-writing methods for human-readable output and endian-specific binary methods for binary formats. A ByteBuffer also implements io.Writer, so code written against that interface can target memory as well as a file or connection.