Welcome to the world of the Leo programming language! I'm Heorhii, and I'll guide you through this comprehensive developer's tutorial on Leo, a functional, statically-typed language designed for building private applications. Let's dive in!
Here are the three advantages of the Leo programming language:
Privacy by design: Leo prioritizes privacy, ensuring that sensitive data remains confidential and secure through zk proofs and cryptographic techniques.
Statically-typed and functional: Leo offers strong type checking and immutable data structures, resulting in more reliable code and fewer runtime errors.
Compilation to Aleo instructions: Leo compiles directly to Aleo Instructions, enabling developers to build applications for the Aleo network with ease, leveraging the power of zk proofs for privacy-preserving dApps.
Installing Leo. To get started, head over to the Installation guide for detailed instructions on installing Leo on your system. Ensure you follow the steps carefully to set up Leo properly.
https://developer.aleo.org/leo/installation/
Getting started. Once you have Leo installed, check out the Hello Leo tutorial to familiarize yourself with Leo and its command-line interface. This tutorial provides a brief walk-through of Leo's core concepts and how to use the Leo CLI efficiently.
# Example Leo CLI usage
leo new my_project
cd my_project
leo run hello
Language guide. Explore Leo's language guide to understand its supported types, syntax, and operators. Start with the basics by learning about data types and values, followed by understanding the layout of a Leo program. You can also refer to the Leo Cheat Sheet for quick syntax references.
// Example Leo program
function main() {
let message = "Hello, Leo!";
return message;
}
Formal language documentation. For a deeper dive into Leo's syntax, check out the formal ABNF grammar specification provided in the documentation. This specification offers a comprehensive view of Leo's syntax rules and structure.
; Example Leo ABNF grammar
program = function-declaration *newline
function-declaration = "function" identifier "(" ")" block
block = "{" *statement "}"
statement = expression ";"
expression = identifier "=" expression
Command line interface documentation. The Leo CLI offers a suite of commands to simplify programming in Leo. Familiarize yourself with essential commands such as leo example, leo new, leo run, leo execute, and more to streamline your development process.
# Example Leo CLI commands
leo example
leo run my_program
leo execute my_program
Additional material. Explore additional developer resources, including examples, community projects, and code editor integrations. Make use of the Leo Style Guide and Common Patterns for formatting your code correctly and adhering to best practices.
https://developer.aleo.org/leo
Examples. Now, let's delve into a practical example to demonstrate Leo's capabilities: a Private Auction.
Private Auction. A first-price sealed-bid auction is conducted between two parties: bidders and an auctioneer. Bidders submit bids without knowing others' bids, and the highest bid wins.
// Example Leo Private Auction program
function main() {
let winningBid = resolve(bid1, bid2);
return winningBid;
}
Auction flow:
Bidding: Bidders submit bids to the auctioneer.
Resolution: the auctioneer resolves bids and selects the winning bid.
Finishing: the auctioneer concludes the auction by awarding the item to the winning bidder.
How to run. Follow the steps below to execute the Private Auction program:
Execute Leo program functions
cd auction
./run.sh
Initialize the Auction.
Bidder 1 Private Key:
APrivateKey1zkpG9Af9z5Ha4ejVyMCqVFXRKknSm8L1ELEwcc4htk9YhVK
Bidder 1 Address:
aleo1yzlta2q5h8t0fqe0v6dyh9mtv4aggd53fgzr068jvplqhvqsnvzq7pj2ke
Bidder 2 Private Key:
APrivateKey1zkpAFshdsj2EqQzXh5zHceDapFWVCwR6wMCJFfkLYRKupug
Bidder 2 Address:
aleo1esqchvevwn7n5p84e735w4dtwt2hdtu4dpguwgwy94tsxm2p7qpqmlrta4
Auctioneer Private Key:
APrivateKey1zkp5wvamYgK3WCAdpBQxZqQX8XnuN2u11Y6QprZTriVwZVc
Auctioneer Address:
aleo1fxs9s0w97lmkwlcmgn0z3nuxufdee5yck9wqrs0umevp7qs0sg9q5xxxzh
Place the first bid.
leo run place_bid aleo1yzlta2q5h8t0fqe0v6dyh9mtv4aggd53fgzr068jvplqhvqsnvzq7pj2ke 10u64
Place the second bid.
leo run place_bid aleo1esqchvevwn7n5p84e735w4dtwt2hdtu4dpguwgwy94tsxm2p7qpqmlrta4 90u64
Select the winner.
leo run resolve "{
owner: aleo1fxs9s0w97lmkwlcmgn0z3nuxufdee5yck9wqrs0umevp7qs0sg9q5xxxzh.private,
bidder: aleo1yzlta2q5h8t0fqe0v6dyh9mtv4aggd53fgzr068jvplqhvqsnvzq7pj2ke.private,
amount: 10u64.private,
is_winner: false.private,
_nonce: 4668394794828730542675887906815309351994017139223602571716627453741502624516group.public
}" "{
owner: aleo1fxs9s0w97lmkwlcmgn0z3nuxufdee5yck9wqrs0umevp7qs0sg9q5xxxzh.private,
bidder: aleo1esqchvevwn7n5p84e735w4dtwt2hdtu4dpguwgwy94tsxm2p7qpqmlrta4.private,
amount: 90u64.private,
is_winner: false.private,
_nonce: 5952811863753971450641238938606857357746712138665944763541786901326522216736group.public
}"
Finish the auction.
Refer to the provided code snippets and instructions for each step to run the Private Auction successfully.
Check my GitHub Auction:
https://github.com/colliseum2006/Aleo-Auction-Leo
Congratulations! You've successfully explored the Leo programming language and executed a Private Auction. Keep experimenting with Leo's features and unleash its potential in building private applications. Happy coding!
In conclusion, the Leo programming language offers developers a powerful toolset for building privacy-focused applications on the Aleo network. With its emphasis on privacy by design, static typing, and seamless compilation to Aleo Instructions, Leo empowers developers to create robust and secure decentralized applications while maintaining user confidentiality. By harnessing the capabilities of Leo, developers can contribute to the advancement of privacy-preserving technologies and drive innovation in the blockchain space.
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Prepared by Colliseum