Lenses for Composable Servers

TL;DR

This paper introduces a novel approach to server development using parameterised lenses, enabling composable and extendable server endpoints and entire servers through lens composition and dependency extension.

Contribution

It presents a new lens-based framework for modeling and composing server endpoints and servers, including dependent parameterised lenses for full server composition.

Findings

Lenses effectively model server state updates and HTTP properties.

Dependent lenses enable composition of entire servers.

Framework supports modular and extendable server design.

Abstract

We implement the semantics of server operations using parameterised lenses. They allow us to define endpoints and extend them using classical lens composition. The parameterised nature of lenses models state updates while the lens laws mimic properties expected from HTTP. This first approach to server development is extended to use dependent parameterised lenses. An upgrade necessary to model not only endpoints, but entire servers, unlocking the ability to compose them together.