Gmail is not built with GWT, it's built with Closure Compiler. Inbox is built with GWT and Closure compiler together, as a hybrid app, with the UI done in Clos

Gmail is not built with GWT, it's built with Closure Compiler. Inbox is built with GWT and Closure compiler together, as a hybrid app, with the UI done in Closure/JS, and the business logic done in Java so it can be shared with Android and iOS. Over the past 2 years, the GWT team has been honing a new JsInterop spec that removes the majority of the impedance mismatch between Java and JS for hybrid apps, which will be part of the 2.8 release. One of my favorite features is automatic Java8 lambda <=> JS function conversion. Any single method interface in Java, when marked with @JsFunction, can be passed to JS where it can be called as a regular JS function, likewise, any JS function can be passed back to any Java function accepting a single-method-interface, and it will pretend to implement the interface. You can now write (GWT 2.8), code like $("ul > li").click(e -> Window.alert('You clicked me')) with only a few lines of code to interface with jQuery for example. You can see a deeper dive here: https://drive.google.com/a/google.com/file/d/0BwVGJUurq6uVR1Y5anV5TC1SQkk/edit https://drive.google.com/a/google.com/file/d/0BwVGJUurq6uVR1...