The Motoko base library

Important update: The Motoko base library has been replaced by the official core package. New projects should use core instead of base.

• GitHub repository
• Core documentation
• Core Mops package
• Migration guide from base to core

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

Usage

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.

Building & Testing

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

Documentation

The documentation can be generated in doc/ by running

./make_docs.sh

which creates _out/html/index.html.

The next-moc branch

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.

• master branch is meant for the newest released version of moc
  • The CI runs on this branch
• next-moc branch is meant for the in-development version of moc
  • This branch is used by the motoko repository's CI

Both branches are kept in sync with each other by mutual, circular merges:

• next-moc is updated automatically on each push to master via the sync.yml workflow
• master is updated manually on each release of moc as part of the motoko release process

Only normal merges are allowed between master and next-moc, because development is permitted on both branches. This policy makes every PR (to either branch) visible in the history of both branches.

Contributing

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