Fluent APIs in Functional Languages (full version)

TL;DR

This paper presents a method for designing fluent APIs in functional programming languages using parametric polymorphism and type inference, enabling compile-time protocol enforcement without relying on function overloading.

Contribution

It introduces a novel approach to implement fluent APIs in functional languages, overcoming the limitations of overloading and supporting complex API protocols.

Findings

Supports all regular and deterministic context-free API protocols

Enables compile-time enforcement of API syntax

Provides a practical alternative to overloading in functional languages

Abstract

Fluent API is an object-oriented pattern for elegant APIs and embedded DSLs. A smart fluent API can enforce the API protocol or DSL syntax at compile time. As fluent API designs typically rely on function overloading, they are hard to realize in functional programming languages. We show how to write functional fluent APIs using parametric polymorphism and type inference instead of overloading. Our designs support all regular and deterministic context-free API protocols and beyond.