This repository contains the Motoko base library. It is intended to be used with the moc compiler (and tools that wrap it, like dfx).

If you are installing Motoko through the DFINITY SDK releases, then this base library is already included.

If you build your project using the Mops package manager, run the following command to add the base package to your project:

mops add base

If you build your project using the Vessel package manager your package-set most likely already includes base, but if it doesn't or you want to override its version, add an entry like so to your package-set.dhall:

  {
    name = "base",
    repo = "https://github.com/dfinity/motoko-base",
    version = "master",
    dependencies = [] : List Text
  }

The package name "base" appears when importing its modules in Motoko (e.g., import "mo:base/Nat"). The repo may either be your local clone path, or this public repository url, as above. The version can be any git branch or tag name (such as version = "moc-0.8.4"). There are no dependencies. See the Vessel package manager docs for more details.

Run the following commands to configure your local development branch:

# First-time setup
git clone https://github.com/dfinity/motoko-base
cd motoko-base
npm install

# Run tests
npm test

# Run all tests in wasi mode
npm test -- --mode wasi

# Run formatter
npm run prettier:format

Note:

• If you are using npm test to run the tests:

  • You don't need to install any additional dependencies.
  • The test runner will automatically download the moc and wasmtime versions specified in mops.toml in the [toolchain] section.

• If you are using Makefile to run the tests:

  • The test runner will automatically detect the moc compiler from your system path or dfx installation.

  • Running the tests locally also requires Wasmtime and Vessel to be installed on your system.

Run only specific test files:

npm test <filter>

For example npm test list will run List.test.mo and AssocList.test.mo test files.

Run tests in watch mode:

npm test -- --watch

# useful to combine with filter when writing tests
npm test array -- --watch

The documentation can be generated in doc/ by running

./make_docs.sh

which creates _out/html/index.html.

The next-moc branch contains changes that make base compatible with the in-development version of moc. This repository's public CI does not run on that branch.

External contributions are best made against master.

Please read the Interface Design Guide for Motoko Base Library before making a pull request.