bevy_pipe_affect
Write systems as pure functions

Normally, Bevy systems perform some state changes as side effects. This crate enables you to instead return Effects as system output.

Effects define an ECS state transition. All common ECS operations have one or more Effect types provided in the library.

These "systems with effects" can then be .pipe(affect)-ed. The affect system will perform the state transition.

This enables a more functional code-style in bevy app development. User-written systems can all be read-only, pure functions. All mutability can be piped out of your code.

This book

This book aims to provide a place for the following pieces of documentation:

• tutorials: lessons detailing the creation of simple games from start to finish
• explanation: clarification of concepts and strategies employed by bevy_pipe_affect, including details about how it works and why
• how-to guides: recommended solutions to common problems, as well as migration guides

This book is not an API reference. For that, please refer to bevy_pipe_affect's documentation on docs.rs.

While this book aims to be comprehensive, it should also be easy to maintain and up-to-date. This is why, in consort with the API reference, documentation for bevy_pipe_affect aims to satisfy The Grand Unified Theory of Documentation. Furthermore, code snippets in this book are automatically tested by bevy_pipe_affect's CI wherever possible with the help of mdBook-Keeper. This should help inform maintainers when changes to the library have made documentation out-of-date. Deployment of this book to github pages is also performed by bevy_pipe_affect's CI automatically on new releases.

Splitting the documentation up this way means that docs are not necessarily meant to be read in order. Some chapters are intended to be read while working on your own project, while others are meant to be more like studying material. The following are good jumping-off points for beginners:

• Motivations explanation
• effects module api reference (a list of effects and constructors provided by the library)

Other resources

This book is not suitable documentation for Bevy. Some resources for learning Bevy include those listed on the Bevy website, as well as the unofficial Bevy Cheat Book.

bevy_pipe_affect's source code is available on github. This repository also contains cargo examples, which can be run after cloning the repository using $ cargo run --release --all-features --example example-name. These examples may be difficult to follow on their own, and many of their strategies are described in this book. When viewing these examples, be careful to checkout the correct git tag for the version of the library you are using. Some changes may have been made to the library or to the examples on the main branch that are not released yet, and trying to apply these to the version of the library you are using can lead to errors.

License

The pages of this book fall under the same license as the rest of the bevy_pipe_affect repository. I.e., this book is dual-licensed under MIT and Apache 2.0 at your option.