Eliom: tierless Web programming from the ground up.

Eliom is a dialect of OCaml for Web programming. It can be used both server and client-side. Server and client sections can also be mixed in the same file using syntactic annotations. This allows one to build a whole application as a single program, in which it is possible to define in a composable way reusable widgets with both server and client behaviors. Our language also enables simple type-safe communication. Eliom matches the specificities of the Web by allowing the programmer to interleave client and server code while maintaining efficient one-way server-to-client communication. We present how the language extensions introduced by Eliom enable a new paradigm for Web programming, and how this paradigm allows building complex libraries easily, safely, and in a composable manner.