Counter DApp

Prerequisites

1. You must have NodeJS version 22.15 or greater installed.

2. Download the latest version of the Compact developer tools from the release page and follow the instructions to install it.

   For example, if you unzipped the Compact compiler in $HOME/bin/compactc:

   export PATH=$PATH:$HOME/bin/compactc

3. Run npm install in the root folder to install all the necessary packages.

4. Compile and build the code in the contract folder before running the code in the counter-cli folder.
   In the contract folder, run this command:

   npm run compact && npm run build

   Follow the instructions in the documentation to install and launch the proof server.

5. Switch to the counter-cli folder and run this command:

   npm run start-testnet-remote

   If you do not have a wallet yet, you will be given the option to create a new one. After getting your address, you can use the official faucet to request coins to deploy a contract on testnet and interact with it.

The counter contract

The contract subdirectory contains:

• the smart contract
• some unit tests to test the smart contract

The source code

The contract contains a declaration of state stored publicly on the blockchain:

export ledger round: Counter;

and a single transition function to change the state:

export circuit increment(): [] {
  round.increment(1);
}

To verify that the smart contract operates as expected, we've provided some unit tests in contract/src/test/counter.test.ts.

We've also provided tests that use a simple simulator, which illustrates how to initialize and call the smart contract code locally without running a node in contract/src/test/counter-simulator.ts

Building the smart contract

Compile the contract:

npm run compact

You should see the following output from npm and the Compact compiler:

Compiling 1 circuits:
  circuit "increment" (k=10, rows=29)

The compiler will complete very quickly because we've instructed it to skip ZK key generation with the option --skip-zk. The compiler's output files will be placed in the directory contract/src/managed/counter.

Build the TypeScript source files:

npm run build

This creates the contract/dist directory.

Start unit tests:

npm run test

CLI

After building the smart contract you can deploy it using the project in the subdirectory counter-cli:

cd ../counter-cli

Build from source code:

npm run build

Run the DApp:

npm run testnet-remote

If you want to launch all these steps at once, you can use this command:

npm run start-testnet-remote

The preceding entry point assumes you already have a proof server running locally. If you want one to be started automatically for you, use instead:

npm run testnet-remote-ps

Then follow the instructions from the CLI.

If you did not previously create and fund a Midnight Lace wallet, you will need to do so. Funds for testing can be requested from the official faucet.

You can find more information in part 2 of the Midnight developer tutorial.