brick: A declarative terminal user interface library

brick is a Haskell terminal user interface (TUI) programming toolkit. To use it, you write a pure function that describes how your user interface should look based on your current application state and you provide a state transformation function to handle events.

brick exposes a declarative API. Unlike most GUI toolkits which require you to write a long and tedious sequence of "create a widget, now bind an event handler", brick just requires you to describe your interface using a set of declarative layout combinators.

Under the hood, this library builds upon vty, so some knowledge of Vty will be helpful in using this library.

Example

Here's an example interface (see programs/ReadmeDemo.hs):

withBorderStyle unicode $
borderWithLabel (str "Hello!") $
(center (str "Left") <+> vBorder <+> center (str "Right"))

Result:

┌─────────Hello!─────────┐
│           │            │
│           │            │
│   Left    │   Right    │
│           │            │
│           │            │
└────────────────────────┘

Featured Projects

To get an idea of what some people have done with brick, take a look at these projects. If you have made something and would like me to include it, get in touch!

These third-party packages also extend brick:

Release Announcements / News

Find out about brick releases and other news on Twitter:

https://twitter.com/brick_haskell/

Getting Started

Check out the many demo programs to get a feel for different aspects of the library:

$ cabal new-build -f demos
$ find dist-newstyle -type f -name \*-demo

To get started, see the user guide.

Documentation

Documentation for brick comes in a variety of forms:

• The official brick user guide
• Samuel Tay's brick tutorial
• Haddock (all modules)
• Demo programs (Screenshots)
• FAQ

Feature Overview

brick comes with a bunch of batteries included:

• Vertical and horizontal box layout widgets
• Basic single- and multi-line text editor widgets
• List widget
• Progress bar widget
• Simple dialog box widget
• Border-drawing widgets (put borders around or in between things)
• Generic scrollable viewports
• General-purpose layout control combinators
• Extensible widget-building API
• User-customizable attribute themes
• Type-safe, validated input form API (see the Brick.Forms module)
• A filesystem browser for file and directory selection
• Borders can be configured to automatically connect!

Brick-Users Discussion

The brick-users Google Group / e-mail list is a place to discuss library changes, give feedback, and ask questions. You can subscribe at:

[https://groups.google.com/group/brick-users](https://groups.google.com/group/brick-users)

Status

There are some places were I have deliberately chosen to worry about performance later for the sake of spending more time on the design (and to wait on performance issues to arise first). brick is also something of an experimental project of mine and some aspects of the design involve trade-offs that might not be right for your application. Brick is not intended to be all things to all people; rather, I want it to provide a good foundation for building complex terminal interfaces in a declarative style to take away specific headaches of building, modifying, and working with such interfaces, all while seeing how far we can get with a pure function to specify the interface.

brick exports an extension API that makes it possible to make your own packages and widgets. If you use that, you'll also be helping to test whether the exported interface is usable and complete!

Reporting bugs

Please file bug reports as GitHub issues. For best results:

• Include the versions of relevant software packages: your terminal emulator, brick, ghc, and vty will be the most important ones.

• Clearly describe the behavior you expected ...

• ... and include a minimal demonstration program that exhibits the behavior you actually observed.

Contributing

If you decide to contribute, that's great! Here are some guidelines you should consider to make submitting patches easier for all concerned:

• If you want to take on big things, talk to me first; let's have a design/vision discussion before you start coding. Create a GitHub issue and we can use that as the place to hash things out.
• Please make changes consistent with the conventions I've used in the codebase.
• Please adjust or provide Haddock and/or user guide documentation relevant to any changes you make.
• New commits should be -Wall clean.
• Please do NOT include package version changes in your patches. Package version changes are only done at release time when the full scope of a release's changes can be evaluated to determine the appropriate version change.