Quickstart

Generate your counter project

Start by creating a new Clarinet project. This command will create a new directory named counter and set up a basic Clarinet project inside it.

clarinet new counter

Navigate to the newly created directory:

cd counter

You should see the following files and folders:

Create a counter contract

Inside your project, create your first contract. This command will create an empty counter.clar file in the contracts folder as well as a counter.test.ts file in the tests folder.

clarinet contract new counter

It also updates the Clarinet.toml file inside your project with the necessary settings.

[contracts.counter]
path = 'contracts/counter.clar'
clarity_version = 2
epoch = 2.5

Variables and functions

In Clarity, you can define variables and functions to store and manipulate data. Inside your contracts/counter.clar file:

1. Define a map called Counters to store the count associated with each user.
2. Define a public function called count-up that increments the count of the user who calls it.
3. Add a read-only function called get-count that returns the count of the user who calls it.

(define-map Counters principal uint)

(define-public (count-up)
  (ok (map-set Counters tx-sender (+ (get-count tx-sender) u1)))
)

(define-read-only (get-count (who principal))
  (default-to u0 (map-get? Counters who))
)

Validate your contract

Now it's time to validate your contract. This command will check your contract for errors and typos.

clarinet check

Once your contract is validated, you can interact with it in a local REPL with the following steps:

1. Run clarinet console from the terminal inside of your project.

clarinet console

2. Call your contract by running (contract-call? .counter count-up).

(contract-call? .counter count-up)

3. Verify the count of the user has been incremented by calling the get-count function with the tx-sender as the argument.

(contract-call? .counter get-count tx-sender)