Play (code) with Cairo language for writing smart contracts on StarkNet L2 chains.

• High level language: cairo
• Sierra serves as an intermediate layer between high-level Cairo and compilation targets such as Cairo Assembly (CASM).
• The diagram below is for .cairo file:

graph LR
  file.cairo --scarb build--> file.sierra
  file.sierra --sierra-compile--> file.casm --deploy--> S[Starknet L2 chain]
  file.cairo --cairo-run--> Run
  file.cairo --cairo-test--> Testing

Install scarb package manager (inspired from cargo).

SOURCE

❯ curl --proto '=https' --tlsv1.2 -sSf https://docs.swmansion.com/scarb/install.sh | sh                                                                                            ⏎
scarb-install: retrieving latest version from https://github.com/software-mansion/scarb...
scarb-install: downloading scarb-v0.5.0-aarch64-apple-darwin.tar.gz...
% Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                Dload  Upload   Total   Spent    Left  Speed
0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
100 19.9M  100 19.9M    0     0  6316k      0  0:00:03  0:00:03 --:--:--  9.7M
scarb-install: installed scarb to /Users/abhi3700/.local/share/scarb-install/latest
scarb-install: created symlink /Users/abhi3700/.local/bin/scarb -> /Users/abhi3700/.local/share/scarb-install/latest/bin/scarb

Detected your preferred shell is zsh and added '$HOME/.local/bin' to PATH. Run 'source /Users/abhi3700/.zshrc' or start a new terminal session to use Scarb.
Then, run 'scarb --version' to verify your installation. Happy coding!

source /Users/abhi3700/.zshrc

Verify the installation:

$ scarb --version

There are many binaries available in bin folder of cairo repo, for them we need to install directly.

• cairo-run
• cairo-test
• starknet-compile
• starknet-sierra-compile

All the required binaries below can be done at once by following this:

1. Creates binaries: cairo-run, cairo-test, starknet-compile, starknet-sierra-compile in target/release/ folder.

   $ cargo build --release --bin cairo-run
   $ cargo build --release --bin cairo-test
   $ cargo build --release --bin starknet-compile
   $ cargo build --release --bin starknet-sierra-compile

2. Just call the binaries from the cairo repo's cloned directory inside a scarb project like this:

   M-1: Using scarb pkg manager:

   [scripts]
   hello = "../cairo/target/release/cairo-run --single-file src/hello.cairo"

   Recommended to give the absolute path of the binaries w.r.t your mac. But for security reasons, given relative path here. We can use env as well. Waiting for better release in future. As of now, this is the best way to use binaries from cairo repo.

   M-2: Using binary directly:

   1. alias the absolute path of the cloned target/release binaries

   # in .zprofile
   $ alias cairorun="absolute/path/to/cairo/target/release/cairo-run"
   $ alias cairotest="absolute/path/to/cairo/target/release/cairo-test"
   $ alias snetcompile="absolute/path/to/cairo/target/release/starknet-compile"
   $ alias snetscompile="absolute/path/to/cairo/target/release/starknet-sierra-compile"

   And then run $ source .zprofile to enable the aliasing.

   2. And then run the hello program like this:

   $ cairorun --single-file src/hello.cairo

VSCode Extensions:

• Cairo 1.0 | StarkWare Industries for language server. Also called "vscode-cairo".
  • Alternatively, can be installed from Github.
• Cairo Syntax highlighting | StarkWare Industries.

In order to install vscode-cairo for language server, follow this steps:

1. Clone cairo repo
2. $ cd vscode-cairo
3. $ npm i
4. $ code --install-extension cairo1*.vsix
5. Now, extension is installed in VSCode.

OR

Directly install the extension from VSCode marketplace.

After the extension is installed, then do this:

1. Press cmd+, in VSCode to open the preferences.
2. type "cairo1" & then put the path of scarb binary & cairo-language-server and save it like this:

Here, the cloned cairo repo path should be added here w.r.t your mac absolute location like "~/cairo/target/release/cairo-language-server"

Congratulations 🎉, you're all set to write Cairo code in VSCode.

1. Created a folder like cairo-playground (like this repo) and then initialize using scarb pkg manager (inspired from cargo).

   $ scarb init --name cairo_playground

   Note: '-' is not allowed in the name of the project.

2. Write a hello code in Cairo like this:

   

3. Get suggestion, errors and warnings from Cairo language server:

   

4. Once entered, the boilerplate (for instance fn) looks like this:

5. All the errors can be found via global find in the repo Cairo repo like this:

6. Build

   $ scarb build

   target/ folder is created containing target/dev/cairo_playground.sierra file.

7. Run cargo file:

   ❯ cairo-run --single-file src/lib.cairo                                                                                                           ⏎
   [DEBUG] Hello, world!                   (raw: 0x48656c6c6f2c20776f726c6421
   
   Run completed successfully, returning []

8. Test

   ❯ scarb run hello_test
   running 2 tests
   test hello::hello::test_works ... ok
   test hello::hello::test_fails ... ok
   test result: ok. 2 passed; 0 failed; 0 ignored; 0 filtered out;

9. Deploy code on StarkNet L2 chain #TODO: How to deploy ???

use debug::PrintTrait;

'Hello, world!'.print();
'z'.print();
z.print();

When run in CLI, it prints like this:

# scarb run hello
❯ scarb run func1
[DEBUG] Hello, world!                   (raw: 0x48656c6c6f2c20776f726c6421
[DEBUG] z:                              (raw: 0x7a3a20

[DEBUG] )                               (raw: 0x29

Run completed successfully, returning []

Here, all the CLI values are in hex format. So, z = 41 (decimal) is represented as 0x29 (hexadecimal).

Write tests in the *.cairo files like this:

#[cfg(test)]
mod tests {
    use super::{add_u8, add_felt252};

    #[test]
    fn test_add_u8() {
        assert(add_u8(1, 2) == 3, '1+2 should be 3');
    }

    #[test]
    #[should_panic(expected: ('1_000_000+2 should be 1_000_002', ))]
    fn test_add_felt252_fails() {
        assert(add_felt252(1_000_000, 2) == 1_000_003, '1_000_000+2 should be 1_000_002');
    }

    #[test]
    #[ignore]
    fn expensive_test() {
         // code that takes an hour to run
    }
}

Setup scarb to run tests like this:

#[dependencies]
func1_test = "../cairo/target/release/cairo-test --single-file src/tuts/functions/func1.cairo"

Run tests in the CLI

$ scarb run func1_test

// 1. Primitive types
let x: felt252 = 1;

// 2. Arrays
let arr: felt252[10] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

• Faucet: https://faucet.goerli.starknet.io/
• Wallet (like Metamask): Braavos
• Explorer:
  • Goerli Starknet: https://goerli.voyager.online/

• Starknet Foundry Book