Move Standard Library (MoveStdlib)

The Move Standard Library (std) provides the foundational types and utilities used across all Move programs. It is deployed at address 0x1.

Source: aptos-framework/move-stdlib

Key Modules

std::string

UTF-8 encoded strings.

use std::string::{Self, String};

let greeting: String = string::utf8(b"Hello, Aptos!");
let length = string::length(&greeting);
let is_empty = string::is_empty(&greeting);

std::vector

Dynamic arrays (see Collections > Vectors for details).

use std::vector;

let v = vector[1, 2, 3];
let len = v.length();

std::option

Optional values -- a value that may or may not be present.

use std::option::{Self, Option};

let some_val: Option<u64> = option::some(42);
let none_val: Option<u64> = option::none();
let val = option::extract(&mut some_val); // 42

std::signer

Functions for working with transaction signers.

use std::signer;

fun get_addr(account: &signer): address {
    signer::address_of(account)
}

std::error

Standard error categories for structured error reporting.

use std::error;

const E_NOT_FOUND: u64 = 1;

fun example() {
    abort error::not_found(E_NOT_FOUND)
}

Error categories include: not_found, already_exists, permission_denied, invalid_argument, invalid_state, out_of_range, resource_exhausted, and internal.

std::bcs

Binary Canonical Serialization (see BCS chapter).

use std::bcs;

let bytes = bcs::to_bytes(&42u64);

std::hash

Cryptographic hash functions.

use std::hash;

let data = b"hello";
let hash = hash::sha3_256(data);

std::debug

Debugging utilities (test-only).

#[test_only]
use std::debug;

#[test]
fun test_debug() {
    debug::print(&42);
}

std::fixed_point32 / std::fixed_point64

Fixed-point arithmetic for precise financial calculations.

use std::fixed_point32::{Self, FixedPoint32};

let half = fixed_point32::create_from_rational(1, 2);
let result = fixed_point32::multiply_u64(100, half); // 50

Summary