Try mruby on your phone!

This app uses the webruby gem. Xuejie Xiao created this to easily compile mruby into JavaScript using emscripten for easy use in the browser. github.com/xxuejie/webruby github.com/kripken/emscripten

Matz created mruby, which is a lighweight Ruby implementation that's easily embeddable. github.com/mruby/mruby

CodeMirror is the javascript editor used. codemirror.net

Setup Instructions:

1. Install cordova
2. For ios emulator: cordova emulate ios
3. Haven't tried but should work on android and other cordova platforms