I searched le interwebs, but I haven't found someone experiencing the same problem as me, so I propose my question here.
I just started using Rails 3.1 with Compass, Haml and CoffeeScript and ran into a problem. When I rename my controller-specific JavaScript file located in app/assets/javascript/index.js to index.js.coffee and translate the JavaScript code to CoffeeScript, everything works as expected - the file is requested by the browser and compiled on the fly into JavaScript. Changes in the CoffeeScript file do also trigger recompilation.
However, when I try to do this with unobtrusive JavaScript (:remote => true) and rename the already working JavaScript file located in the view folder app/views/index/index.js.haml to index.js.coffee.haml and translate the included code, Rails doesn't recognize it as a CoffeeScript that needs to be compiled.
What am I doing wrong? Do I actively have to enable CoffeeScript evaluation for the view? Where?
The asset pipeline introduced in Rails 3.1 will automatically compile coffeescript assets into javascript for you, as you've mentioned. This is currently NOT the case for views: only files in app/assets/javascripts will be compiled.
To use Coffeescript in views, you'll need to use https://github.com/markbates/coffeeBeans for the time being.
Update : per Kyle Heironimus' comment below, it seems this functionality can be provided by coffe-rails (see https://github.com/rails/coffee-rails and http://rubygems.org/gems/coffee-rails )