A Pop project

A single source file is enough for small examples. As a program grows, keeping its source and project information together makes it easier to run and share. Pop calls this unit a Bubble and describes it with a bubble.toml file.

Create a new directory with this layout:

greeting/
├── bubble.toml
└── src/
    └── main.pop

Put the following project information in bubble.toml:

bubble.toml

[package]
name = "Greeting"
version = "0.1.0"
edition = "2026"

The package name uses PascalCase, just like the namespace in the source file. The version identifies this project, not the installed version of Pop.

Now add the program:

src/main.pop

namespace Greeting

function main()
    print("Hello from a Pop project!")
end

From the greeting directory, run:

pop run --manifestPath bubble.toml

Pop reads the manifest, discovers src/main.pop, builds the program under target/debug/, and runs it.

The conventional layout

src/main.pop is the default executable source. A project may instead or additionally contain a reusable src/lib.pop. Extra executables can live in src/bin/, although the current run command needs the project to contain exactly one executable.

The manifest format also recognizes a [dependencies] table, but dependency resolution is not available in 0.1.0-rc.2. For now, use a Bubble to organize code that belongs to one project; do not expect it to download external packages.

We will use direct .pop files for most short examples because they keep the lesson focused. The Modules and Packages part returns to multi-file organization and the complete project layout.