Coding Verifiable Components

Proven Network uses a virtual machine which can run code targeting the WASM Component Model. Let's look at an example component!

wit/rock-paper-scissors.wit

package component:rps-example;

world rps-example {
  import @proven-network:storage/identity-kv;
  
  enum move {
    rock,
    paper,
    scissors,
  }

  enum outcome {
    win,
    loss,
    draw,
  }

  record metrics {
    played: u32,
    won: u32,
    lost: u32,
    drawn: u32,
  }

  export play: func(move: move) -> outcome;
  export score: func() -> metrics;
}

Here we're defining a simple rock-paper-scissors games which allows player to call a play function with their selected move and get an outcome in return.

WIT files are used by language-specific build tools to automatically handle all required codegen. Let's implement the play function in Rust using the cargo-component tooling.

src/lib.rs

mod bindings; // This module is automatically generated by cargo-component

use bindings::{
    Guest, Metrics, Move,
    Move::{Paper, Rock, Scissors},
    Outcome,
    Outcome::{Draw, Loss, Win}
};

use rand::Rng;

struct Component;

impl Guest for Component {
    fn play(input: Move) -> Outcome {
        let server_selection = [Rock, Paper, Scissors][rand::thread_rng().gen_range(0..3)];

        match (input, server_selection) {
            (Rock, Scissors) | (Scissors, Paper) | (Paper, Rock) => Win,
            (Rock, Rock) | (Scissors, Scissors) | (Paper, Paper) => Draw,
            _ => Loss,
        }
    }
}

bindings::export!(Component with_types_in bindings);

Accessing persistent storage

Coming soon

Further reading on the Webassembly Component Model

Further documentation on the WA Component Model can be found on the Bytecode Alliance documentation site: https://component-model.bytecodealliance.org/