zero

Learn

Getting Started

Install Zero, check a file, and run your first program.

Getting Started

Zero is the programming language for agents. The fastest way to try it today is to install the latest compiler release and run a small program.

Install The Compiler

curl -fsSL https://zerolang.ai/install.sh | bash
export PATH="$HOME/.zero/bin:$PATH"
zero --version

The installer downloads the latest matching binary from the GitHub release and writes it to $HOME/.zero/bin/zero.

Check Your First File

Create hello.0:

pub fun main(world: World) -> Void raises {    check world.out.write("hello from zero\n")}

Run the checker:

zero check hello.0

The important parts are:

  • pub fun main(...) declares the program entry point.
  • world: World is the capability object passed to the program by the runtime.
  • world.out.write(...) writes through that explicit capability.
  • check handles a fallible operation.
  • raises marks that main can return an error.

Zero makes effects visible. A program that writes output asks for World instead of reading a hidden global process object.

Build And Run An Executable

Create add.0:

fun answer() -> i32 {    return 40 + 2} pub fun main(world: World) -> Void raises {    let value = answer()    if value == 42 {        check world.out.write("math works\n")    } else {        check world.out.write("math broke\n")    }}

Run it:

zero run add.0

Expected output:

math works

This example introduces a helper function, a local binding, and if / else.

Create A Package

The project workflow starts with zero new:

zero new cli hello
cd hello
zero check .
zero test .
zero run .
zero build --target linux-musl-x64 --out .zero/out/hello .

Single files are useful for learning, but real Zero projects use a zero.json manifest and source files under src/.

Learn The Core Syntax

Work through these examples in order:

zero check examples/hello.0
zero check examples/hello-let.0
zero check examples/functions.0
zero check examples/branch.0
zero check examples/point.0
zero check examples/result-choice.0

They cover:

  • entry points and output
  • let bindings
  • functions and return values
  • conditionals
  • shape data declarations
  • enum, choice, and match

Inspect A Package

The CLI package example lives in examples/systems-package:

examples/
  systems-package/
    src/
      main.0
      helpers.0
      types.0
    zero.json

Check it:

zero check examples/systems-package

Inspect its module graph:

zero graph --json examples/systems-package

The manifest tells Zero where the entry point lives:

{
  "package": { "name": "systems-package", "version": "0.1.0" },
  "targets": { "cli": { "kind": "exe", "main": "src/main.0" } }
}

Next Steps

  • Read Learn Zero for a practical language tour.
  • Use the examples index to pick the next example by concept.
  • Use Building From Source when you want to validate a local checkout.
  • Use the language reference once you have written a few small programs.