Skip to main content

Hello World in Leo

Use the Leo CLI to create a new project. In your terminal, run:

leo new hello
cd hello

This creates a directory with the following structure:

├── program.json # Your program manifest
├── # Your program description
├── inputs/
│ ├── # Your program inputs
└── src/
└── main.leo # Your program file

Let's run the project.

Zero Knowledge in one line

The leo run command will compile and execute the program. In your terminal, run:

leo run main
console output:
 Build ✅ Compiled 'main.leo' into Aleo instructions (in "/hello/build/main.aleo")
⏳ Compiling 'hello.aleo'...

• Loaded universal setup (in 100 ms)
• Built 'main' (in 1000 ms)

Build ✅ Built 'hello.aleo' (in "/hello/build")
• Loaded universal setup (in 100 ms)
🚀 Executing 'hello.aleo/main'...

• Executing 'hello.aleo/main'...
• Executed 'main' (in 1000 ms)

➡️ Output

• 3u32

Executing ✅ Executed 'hello.aleo/main' (in "/hello/build")

Congratulations! You've just run your first Leo program.

Let's go through the file syntax of the program we just executed.