raintree-technology/aptos

Aptos Blockchain & Move Language Expert

Aptos is a Layer 1 blockchain with the Move programming language, designed for safe and scalable smart contracts.

When to Use

• Writing Move smart contracts
• Understanding Move type system (abilities, generics, resources)
• Using Aptos framework modules (coin, fungible_asset, object)
• Token standards (Coin, Fungible Asset, Digital Asset/NFT)
• Gas optimization and testing
• dApp integration with TypeScript SDK

Move Language Fundamentals

Abilities - Move's Core Feature

Every type has abilities that control what you can do with it:

| Ability | Meaning | Example | |---------|---------|---------| | copy | Can be duplicated | Primitives, configs | | drop | Can be discarded | Temporary data | | store | Can be stored in structs | Most data types | | key | Can be top-level resource | Account resources |

// Resource that can be stored globally
struct Balance has key, store {
    coins: u64
}

// Value type that behaves like a primitive
struct Point has copy, drop, store {
    x: u64,
    y: u64
}

// No abilities = must be explicitly handled (hot potato)
struct Receipt {
    amount: u64
}

Generics and Phantom Types

// Type parameter with ability constraint
struct Box<T: store> has key {
    value: T
}

// Phantom type - zero runtime cost, type safety only
struct Coin<phantom CoinType> has store {
    value: u64
}

// Different types can't be mixed
let btc: Coin<BTC> = Coin { value: 100 };
let eth: Coin<ETH> = Coin { value: 50 };
// btc + eth → compile error!

Global Storage Operations

// Store resource at signer's address
public fun initialize(account: &signer) {
    move_to(account, MyResource { value: 0 });
}

// Read resource (requires acquires annotation)
public fun get_value(addr: address): u64 acquires MyResource {
    borrow_global<MyResource>(addr).value
}

// Modify resource
public fun set_value(addr: address, val: u64) acquires MyResource {
    borrow_global_mut<MyResource>(addr).value = val;
}

// Check existence
public fun exists_at(addr: address): bool {
    exists<MyResource>(addr)
}

// Remove and return resource
public fun destroy(addr: address): MyResource acquires MyResource {
    move_from<MyResource>(addr)
}

Signer - Authentication

use std::signer;

// Only the account owner can call this
public entry fun transfer(
    sender: &signer,
    recipient: address,
    amount: u64
) acquires Balance {
    let sender_addr = signer::address_of(sender);
    // sender proves ownership of sender_addr
}

Visibility Modifiers

module example {
    // Private (default) - only within module
    fun internal() { }

    // Public - callable from anywhere
    public fun library_fn() { }

    // Friend - only from declared friend modules
    public(friend) fun restricted() { }

    // Entry - transaction entry point
    public entry fun user_action(account: &signer) { }
}

Aptos Framework (0x1)

Core Modules

| Module | Purpose | |--------|---------| | account | Account creation, auth key rotation | | coin | Original fungible token standard | | fungible_asset | New flexible token standard | | object | Object model for composable assets | | aptos_coin | Native APT token | | timestamp | Block timestamp | | event | Event emission |

Coin Standard (0x1::coin)

use aptos_framework::coin;

// Register to receive a coin type
public entry fun register<CoinType>(account: &signer) {
    coin::register<CoinType>(account);
}

// Transfer coins
public entry fun transfer<CoinType>(
    from: &signer,
    to: address,
    amount: u64
) {
    coin::transfer<CoinType>(from, to, amount);
}

// Check balance
public fun balance<CoinType>(addr: address): u64 {
    coin::balance<CoinType>(addr)
}

Fungible Asset Standard (0x1::fungible_asset)

Modern, flexible token standard:

use aptos_framework::fungible_asset::{Self, FungibleAsset, Metadata};
use aptos_framework::primary_fungible_store;

// Create fungible asset metadata
public fun create_fa(creator: &signer): Object<Metadata> {
    let constructor_ref = object::create_named_object(creator, b"MY_FA");
    
    primary_fungible_store::create_primary_store_enabled_fungible_asset(
        &constructor_ref,
        option::none(), // max supply
        utf8(b"My Token"),
        utf8(b"MTK"),
        8, // decimals
        utf8(b"https://example.com/icon.png"),
        utf8(b"https://example.com"),
    );
    
    object::object_from_constructor_ref(&constructor_ref)
}

// Transfer FA
public entry fun transfer_fa(
    sender: &signer,
    metadata: Object<Metadata>,
    recipient: address,
    amount: u64
) {
    primary_fungible_store::transfer(sender, metadata, recipient, amount);
}

Object Model (0x1::object)

Composable, transferable objects:

use aptos_framework::object::{Self, Object, ConstructorRef};

struct MyObject has key {
    value: u64
}

// Create object
public fun create(creator: &signer): Object<MyObject> {
    let constructor_ref = object::create_object(signer::address_of(creator));
    let object_signer = object::generate_signer(&constructor_ref);
    
    move_to(&object_signer, MyObject { value: 42 });
    
    object::object_from_constructor_ref(&constructor_ref)
}

// Transfer object
public entry fun transfer_object(
    owner: &signer,
    obj: Object<MyObject>,
    recipient: address
) {
    object::transfer(owner, obj, recipient);
}

Token Standards

Digital Asset (NFT) Standard

use aptos_token_objects::collection;
use aptos_token_objects::token;

// Create collection
public entry fun create_collection(creator: &signer) {
    collection::create_unlimited_collection(
        creator,
        utf8(b"My Collection Description"),
        utf8(b"My Collection"),
        option::none(), // royalty
        utf8(b"https://example.com/collection"),
    );
}

// Mint token
public entry fun mint_token(creator: &signer, to: address) {
    let token_constructor_ref = token::create(
        creator,
        utf8(b"My Collection"),
        utf8(b"Token description"),
        utf8(b"Token #1"),
        option::none(), // royalty
        utf8(b"https://example.com/token/1"),
    );
    
    let transfer_ref = object::generate_transfer_ref(&token_constructor_ref);
    let linear_transfer_ref = object::generate_linear_transfer_ref(&transfer_ref);
    object::transfer_with_ref(linear_transfer_ref, to);
}

Common Patterns

Capability Pattern

struct AdminCap has key, store {}

public fun init_module(deployer: &signer) {
    move_to(deployer, AdminCap {});
}

public entry fun admin_only(admin: &signer) acquires AdminCap {
    assert!(exists<AdminCap>(signer::address_of(admin)), E_NOT_ADMIN);
    // Admin-only logic
}

Resource Account

use aptos_framework::resource_account;

// Create resource account for deterministic addresses
public fun create_resource_account(creator: &signer): signer {
    let (resource_signer, _cap) = resource_account::create_resource_account(
        creator,
        b"seed"
    );
    resource_signer
}

Events

use aptos_framework::event;

#[event]
struct TransferEvent has drop, store {
    from: address,
    to: address,
    amount: u64,
}

public fun emit_transfer(from: address, to: address, amount: u64) {
    event::emit(TransferEvent { from, to, amount });
}

Testing

#[test]
fun test_basic() {
    let x = 1 + 1;
    assert!(x == 2, 0);
}

#[test(account = @0x123)]
fun test_with_signer(account: &signer) {
    let addr = signer::address_of(account);
    assert!(addr == @0x123, 0);
}

#[test]
#[expected_failure(abort_code = E_NOT_FOUND)]
fun test_expected_failure() {
    abort E_NOT_FOUND
}

CLI Commands

# Initialize project
aptos init

# Compile
aptos move compile

# Test
aptos move test

# Publish
aptos move publish --profile mainnet

# Run function
aptos move run --function-id 'addr::module::function'

Gas Optimization

• Use inline for small frequently-called functions
• Prefer Table over vector for large collections
• Minimize storage operations (most expensive)
• Use SmartTable for parallel execution
• Batch operations when possible

TypeScript SDK

import { Aptos, AptosConfig, Network } from "@aptos-labs/ts-sdk";

const config = new AptosConfig({ network: Network.MAINNET });
const aptos = new Aptos(config);

// Query account balance
const balance = await aptos.getAccountAPTAmount({
    accountAddress: "0x1"
});

// Submit transaction
const txn = await aptos.transaction.build.simple({
    sender: account.accountAddress,
    data: {
        function: "0x1::coin::transfer",
        typeArguments: ["0x1::aptos_coin::AptosCoin"],
        functionArguments: [recipientAddress, amount],
    },
});

const result = await aptos.signAndSubmitTransaction({
    signer: account,
    transaction: txn,
});

Resources

• Docs: https://aptos.dev
• Move Book: https://move-book.com
• Framework: https://github.com/aptos-labs/aptos-core/tree/main/aptos-move/framework
• SDK: https://github.com/aptos-labs/aptos-ts-sdk