Ethereum? Ewww!

Ethereum sucks. At least, in my opinion. 🤷🏽‍♂️ Who the hell wants to deal with those ridiculous gas fees to do literally anything on the network? To me, it's complete garbage. I was learning Solidity, which on it's own is a nice programming language that I appreciate and am thankful for, but... thanks to Stacks and Clarity, I don't have to program for what I consider to be one of the worst networks in all of crypto. Instead, I can create smart contracts for Bitcoin!

Clarity is a domain-specific language (DSL) designed for writing smart contracts on the Bitcoin network. It was created by Blockstack PBC to enhance the security and predictability of Bitcoin smart contracts.

Clarity is designed to be readable, understandable, and deterministic, making it suitable for programming smart contracts with real-world financial implications.

Below, I give a quick intro to the basics of coding in the Clarity language for Bitcoin smart contracts:

Variables & Types

Variables are declared using var keyword. Clarity is a statically-typed language, meaning you must declare the type of a variable when you define it.
Common data types include int, bool, buff (byte string), and more.

(var myVar int)
(var isApproved bool)
(var data buff)

Functions

Functions are defined using (define-fun). They are used to perform actions and return values.
Function names should be in camelCase.

(define-fun addNumbers (a int b int) int
  (+ a b))

Contracts

A contract is the main structure for a Clarity smart contract. It defines the contract's state and functions.
The (define-contract) keyword is used to declare a contract.

(define-contract myContract
  (variable (balance int))
  (public (init (balance int)
    (begin
      (set balance balance))))
  (public (get-balance () int
    balance))

Public & Private Functions

Functions can be marked as public or private. Public functions can be called externally, while private functions are for internal use within the contract.

Transactions & Callers

Clarity contracts can specify who is allowed to call their functions by using the (contract-call?) function.
Bitcoin transactions that execute a Clarity contract are identified as "callers."

(assert
  (contract-call?
    (caller)
    (this-contract)))

Conditionals and Loops

Clarity supports conditional statements like if and loops like while for more complex logic.

(if (isApproved)
  (set balance (+ balance 100)))

Error Handling

Clarity provides the (assert) function for error handling. If an assertion fails, the contract execution is halted.

(assert (>= balance 0))

Testing

Clarity has a built-in testing framework for writing unit tests for your smart contracts. You can use the test keyword to define test cases.

(test (assert-eq (addNumbers 5 7) 12))

Immutable Data

Data stored on the Bitcoin blockchain is immutable. Changes to data in a Clarity contract result in a new contract state.

Deployment

You can deploy a Clarity contract on the Stacks blockchain, a layer-1 blockchain built on top of Bitcoin, using the stacks-transactions tool or a similar tool.

And that's about it! Those are the basic concepts of coding in the Clarity language for Bitcoin smart contracts. I hope this just lit a fire under your ass and you're now as pumped as I am about the future of Bitcoin! 😁

Code On