Your first program

Follow this page exactly after Install. Every command assumes you have vow on your PATH.

1. Scaffold a project

vow new hello-app
cd hello-app
ls src/main.vow project.toml

vow new creates:

File	Purpose
`src/main.vow`	Entry point (`main` in `project.toml`)
`project.toml`	Project name, version, deps
`vow.lock`	Lockfile (empty deps initially)
`README.md`	Build/run commands

Default src/main.vow:

fn main(caps: Caps) -> int {
    print("Hello from Vow!")
    return 0
}

Every program’s entry point is fn main(caps: Caps) -> int. Capabilities enter only here. If you never use caps, you still must declare it.

vow check src/main.vow

Expected: ok: src/main.vow

vow run src/main.vow
echo $?

Expected output includes Hello from Vow! and exit code 0.

vow build src/main.vow -o hello-app
./hello-app
echo $?   # 0

The -o name can match the project name or anything you like; it is not required to be hello.vow.

You do not need vow new for a one-off script. Create hello.vow in any directory:

fn main(caps: Caps) -> int {
    return 1 + 2;
}

vow build hello.vow -o hello
./hello
echo $?   # 3

Or vow run hello.vow.

fn unwrap_or(opt: Option<int>, fallback: int) -> int {
    return match opt {
        Some(x) => x,
        None => fallback
    };
}