Conditional transfer and small programs

Short programs that each show one part of the language. The first is from the compiler’s introduction; the rest ship as example sources under dev-tools/sauce/ts/ inside @eco-incorp/sauce. Compile them with @eco-incorp/sauce/compiler and run them through your Pot as in Getting started; the package’s older local-network scripts under dev-tools/scripts target an earlier contract interface and are not compatible with current deployments.

Prerequisites

Complete Sauce setup and use the documented SDK and compiler versions. For execution, confirm the target deployment, Pot ownership, balances and Kitchen fee. Simulate the complete transaction and estimate its gas before submitting it.

Conditional native transfer

Send native value to the supplied recipient only if the Pot holds enough.

function main(recipient, amount) {
  const balance = ctx.balance(ctx.self());
  if (balance >= amount) {
    evm.call(recipient, amount, hex``);
  }
  return balance;
}

Arithmetic with an input check

example.ts

// Add two values after requiring a positive first input.
function main(a: Uint256, b: Uint256): Uint256 {
  if (!(a > 0)) throw "a must be positive";
  return a + b;
}

Addition

add.ts

// Simple addition example
function main(a: Uint256, b: Uint256): Uint256 {
  return a + b;
}

Contract call: Uniswap V3 factory lookup

Imports the factory ABI from an npm package and looks up a pool address.

call.ts

// Uniswap V3 Pool Lookup
// Imports the factory ABI from @uniswap/v3-core and looks up a pool address
import { IUniswapV3Factory } from "@uniswap/v3-core/artifacts/contracts/interfaces/IUniswapV3Factory.sol/IUniswapV3Factory.json";

function main(factoryAddress: Address, token0: Address, token1: Address): Address {
  const factory = IUniswapV3Factory.at(factoryAddress);
  return factory.getPool(token0, token1, 3000);
}

The three main parameters (factory, token0, token1) arrive as ABI-encoded arguments appended to the compiled program. The import resolves through the compiler’s resolvePackage hook, so @uniswap/v3-core must be installed in the project that compiles it.

ERC-20-like transfer: storage, crypto, ABI encoding and events

erc20.ts

// ERC20-like transfer operation
// Demonstrates: storage, crypto, abi encode/decode, events, ctx.msgSender()

function balanceSlot(account: Address): Uint256 {
  return crypto.keccak256(abi.encode(account, 1));
}

function main(to: Address, amount: Uint256): Uint256 {
  const from = ctx.msgSender();
  const fromSlot = balanceSlot(from);
  const fromBalance = evm.sload(fromSlot);
  if (fromBalance < amount) throw "insufficient balance";
  evm.sstore(fromSlot, fromBalance - amount);
  const toSlot = balanceSlot(to);
  evm.sstore(toSlot, evm.sload(toSlot) + amount);
  log(abi.encode(from, to, amount), crypto.keccak256("Transfer(address,address,uint256)"));
  return 1;
}

Fibonacci: loops and locals

fibonacci.ts

// Calculate fibonacci number
function main(n: Uint256): Uint256 {
  if (n <= 1) return n;

  let a: Uint256 = 0;
  let b: Uint256 = 1;
  for (let i: Uint256 = 2; i <= n; i++) {
    const temp: Uint256 = a + b;
    a = b;
    b = temp;
  }
  return b;
}

Troubleshooting

If an import cannot be resolved, check your resolver and installed ABI package. EVM-specific calls and storage builtins in these examples require target: "evm". Arithmetic overflow or a failed require or throw condition reverts execution.

Next steps

Read the SauceScript reference or try the best-pool swap.

Cookbook

Send & swap

Deposit & payout

Sauce programs

Solvers

Conditional transfer and small programs

Prerequisites

Conditional native transfer

Arithmetic with an input check

Addition

Contract call: Uniswap V3 factory lookup

ERC-20-like transfer: storage, crypto, ABI encoding and events

Fibonacci: loops and locals

Troubleshooting

Next steps

​Prerequisites

​Conditional native transfer

​Arithmetic with an input check

​Addition

​Contract call: Uniswap V3 factory lookup

​ERC-20-like transfer: storage, crypto, ABI encoding and events

​Fibonacci: loops and locals

​Troubleshooting

​Next steps

Prerequisites

Conditional native transfer

Arithmetic with an input check

Addition

Contract call: Uniswap V3 factory lookup

ERC-20-like transfer: storage, crypto, ABI encoding and events

Fibonacci: loops and locals

Troubleshooting

Next steps