Palimpsest

Palimpsest is a new web framework which takes a fresh approach to some of the longstanding conventions of the genre.

Instead of "routes" which run arbitrary code, Palimpsest divides an application into "inputs", "folds", "outputs", and "views". An "input" is more or less a dumb bucket for user input. A fold transforms that raw data into useful formats. An output provides a live readout of user-customized data from one or more folds. And a view shows output data to the user, and sends user input to inputs.

Why organize things in this way? Because inputs are a raw data record, they can be reused as a program evolves to serve different purposes. Because folds are an immutable summary of inputs, rather than an imperative "action" effecting database state, they can be rerun at will. Because outputs are a live event stream, Palimpsest applications are live by default, with no extra effort required to make reactive widgets like chat. Because Palimpsest stores its data as immutable records in a key-value store, rather than mutable database tables, caching can be done correctly without constant programmer input and effort.

Comprehensive documentation is on the way, but for now you can find examples within the example directory, and some explanatory content at my blog.