Adding a MoonBit Package Dependency

Overview

MoonBit projects manage dependencies through the moon.mod.json file at the project root. Dependencies are published on mooncakes.io  and installed with the moon CLI.

Steps

1. Edit moon.mod.json — add the package to the "deps" section
2. Run moon install — download and install the dependency
3. Use the package — import it in your .mbt files

Adding a Dependency

Edit moon.mod.json and add the package under the "deps" object with a version constraint:

{
  "name": "my-org/my-project",
  "version": "0.1.0",
  "deps": {
    "example/json-utils": "0.2.0"
  }
}

Then install:

moon install

Version Constraints

Specify the version as a string in moon.mod.json. Use the exact version published on mooncakes.io.

Using the Dependency

After installation, reference the package in your moon.pkg.json file’s "import" section and use it in your .mbt source files.

In moon.pkg.json:

{
  "import": [
    "example/json-utils"
  ]
}

Key Constraints

• Only packages published on mooncakes.io  can be added as dependencies
• Ensure the package is compatible with the wasm / wasm-gc backend — some MoonBit packages may only support native or JS targets
• After adding a dependency, always run moon install before golem build
• Check the package’s documentation on mooncakes.io for usage examples and API reference