Introduction

In the previous tutorial, we learned how to build a Descartes DApp that is capable of receiving input data as a string and performing a mathematical calculation using the Linux bc tool. In this project, we will generalize this idea to show how Descartes can be leveraged to allow a smart contract to perform a generic computation by receiving an arbitrary script as input and using any interpreter of choice, such as Python or Lua, including any required libraries, to execute it. And without compromising on decentralization.

As always, a full implementation of this tutorial is available in the Descartes Tutorials GitHub repo.

Initializing the DApp project

As we did for the other DApps, we will first initialize our project by creating an appropriate directory and using Truffle to create its basic structure:

mkdir generic-script
cd generic-script
truffle init

We should not forget to edit the generated truffle-config.js file, so that we can properly interact with our development environment's Ganache CLI instance, which is running on port 8545 and has network ID 7777:

networks: {
  development: {
   host: "127.0.0.1",     // Localhost (default: none)
   port: 8545,            // Ganache CLI port (default: none)
   network_id: "7777",    // Environment network (default: none)
  },
},

Last but not least, let's add the necessary dependencies to the Descartes SDK and Truffle:

yarn add @cartesi/descartes-sdk@0.2.0
yarn add @truffle/contract --dev