Awesome Open Source
Awesome Open Source

Purple Train

Purple Train is a mobile app that provides schedules, predictions, and alerts for MBTA Commuter Rail riders.

The app is written in the elm language, using the experimental elm-native-ui library. See the Elm Native UI in Production blog post about why we are excited about writing mobile apps in elm.


  • Make sure you have elm v0.18 installed
  • Run bin/setup


Run yarn run watch

This will start a watch server, which will recompile the elm files when they are saved.

We recommend using elm-format with your editor. You can set it up to format your Elm files when automatically saving them.

Running the app

Run yarn run start to start the react native packager, which will serve the javascript bundle to your mobile devices and simulators.


Open ios/PurpleTrain.xcodeproj and run the project to launch an iPhone simulator.


Follow the React Native Getting Started guide to create and run a virtual Android device.


See the CONTRIBUTING document. Thank you, contributors!

Updating dependencies

Updating elm packages for this project is more complicated than most. See for detailed instructions.

Releasing a new version



Purple Train is Copyright (c) 2016-2017 Josh Steiner, Ian C. Anderson, and thoughtbot, inc. It is free software, and may be redistributed under the GPL license detailed in the LICENSE file.

About thoughtbot


Purple Train is maintained and funded by thoughtbot, inc. The names and logos for thoughtbot are trademarks of thoughtbot, inc.

We love open source software, Elm, and React Native. Work with thoughtbot's React Native development team to design, develop, and grow your product.

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