tornado-core/migrations/4_deploy_mixer.js

require('dotenv').config({ path: '../.env' })
const Mixer = artifacts.require("Mixer");
const Verifier = artifacts.require("Verifier");
const MiMC = artifacts.require("MiMC");


module.exports = function(deployer) {
  return deployer.then(async () => {
    const { MERKLE_TREE_HEIGHT, AMOUNT, EMPTY_ELEMENT } = process.env
    const verifier = await Verifier.deployed()
    const miMC = await MiMC.deployed()
    await Mixer.link(MiMC, miMC.address)
    const mixer = await deployer.deploy(Mixer, verifier.address, AMOUNT, MERKLE_TREE_HEIGHT, EMPTY_ELEMENT)
    console.log("Mixer's address ", mixer.address)
  })
};