Overview

WASM provides a secure and properly sandboxed execution environment for contracts execution. As for now - Rust is being supported.

info

Historically Warp Contracts SDK had a support for Go and AssemblyScript. Because of some technical issues, immaturity and lack of interest in the community - we've decided to focus on Rust. The support for AS and Go has been removed in this PR.

WASM contracts templates containing example PST contract implementation within tools for compiling contracts to WASM, testing, deploying (locally, on testnet and mainnet) and writing interactions are available here.

Using SDKs' methods works exactly the same as in case of a regular JS contract. While deploying the contract, you just need to pass some additional arguments:

const contractTxId = await warp.deploy({
  wallet,
  initState: JSON.stringify(initialState),
  src: contractSrc,
  wasmSrcCodeDir: path.join(__dirname, '../data/wasm/rust/src'),
  wasmGlueCode: path.join(__dirname, '../data/wasm/rust/rust-pst.js'),
});

Additionally, it is possible to set gas limit for interaction execution in order to e.g. protect a contract against infinite loops. Defaults to Number.MAX_SAFE_INTEGER (2^53 - 1).

contract = smartweave.contract(contractTxId).setEvaluationOptions({
  gasLimit: 14000000,
});

Warp-contracts crate

To help writing rust contracts SDK delivers convenient rust crate called warp-contracts. See docs on docs.rs for details of provided API.

The simplest rust contract

The simplest rust contract using warp-contracts crate may look like this:

Source https://github.com/warp-contracts/warp-wasm-templates/blob/main/rust/toy-contract/Cargo.toml

[package]
name = "toy-contract"
version = "0.1.0"
edition = "2021"
description = "test"
repository = "not applicable"
license = "MIT"

[lib]
crate-type = ["cdylib"]

[dependencies]
warp-contracts = "0.1.2"
wasm-bindgen = "=0.2.84"
wasm-bindgen-futures = { version = "0.4.34" }
serde = { version = "1.0", features = ["derive"] }
serde-wasm-bindgen = "0.5"
js-sys = "0.3.61"

Source https://github.com/warp-contracts/warp-wasm-templates/blob/main/rust/toy-contract/src/lib.rs

use serde::{Serialize, Deserialize};
use warp_contracts::{warp_contract, handler_result::{WriteResult, ViewResult}};

#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct State {
    x: u8,
}

#[derive(Debug, Deserialize)]
pub struct Action {
    x: u8,
}

#[derive(Debug, Serialize)]
pub struct View {
    x: u8,
}

#[warp_contract(write)]
pub fn handle(mut state: State, action: Action) -> WriteResult<State, ()> {
    state.x = action.x;
    WriteResult::Success(state)
}

#[warp_contract(view)]
pub fn view(state: &State, _action: Action) -> ViewResult<View, ()> {
    ViewResult::Success(View { x: state.x })
}