My experience with Lean 4 for general programming (quamserena.com)

The author shares insights from their exploration of Lean 4, a powerful proof assistant that doubles as a programming language, focusing on its features and personal projects. Lean 4 allows users to write algorithms and simultaneously prove their correctness within the same environment, a unique advantage for formal verification. The author has undertaken a project to create a reactive HTML library using Lean, aiming to improve efficiency compared to popular frameworks like React by generating minimal client-side JavaScript alongside server-rendered HTML, thus minimizing unnecessary Virtual DOM diffing. This project spotlights Lean's capabilities as not just a tool for theorem proving but also as a viable option for general programming tasks, despite lacking widespread adoption in that area. The author appreciates Lean's extensible syntax, which allows for in-line syntax definitions and supports metaprogramming features, enabling them to create custom components easily. However, they note challenges such as insufficient documentation and obscure error messages, which can complicate the learning curve. The exploration of Lean 4 underscores its potential to influence programming languages design and highlights ongoing challenges in documentation and community support that need addressing for broader adoption.