Alloy Analyzer vs Lean

Alloy Analyzer is a free model-checking tool for describing systems in the Alloy language and exploring the structures those descriptions permit. It searches for structures that satisfy constraints and for counterexamples to properties. Models can represent collections of structures that change over time, including security configurations and switching network topologies. The Analyzer presents results graphically, with appearance options that can be tailored to a domain. Alloy 6 adds mutable state, temporal logic, and temporal model checking; that checking requires NuSMV or nuXmv to be installed and available in PATH. The self-contained executable includes the Pardinus/Kodkod model finder, SAT solvers, the standard Alloy library, tutorial examples, and source code. The same JAR can be used as an API in other applications. Sterling adds a web-based visualizer with graph and table views, customizable and extendable with JavaScript. Alloy is self-hosted, supports Linux, macOS, Windows, and API use, and is maintained by volunteers.

Lean is an open-source programming language and proof assistant for formalizing mathematics, verifying software, and writing general code. Its minimal trusted kernel checks proofs, and the project describes it as supporting correctness in mathematical, software, and hardware verification. Lean includes the Grind tool for automating some pattern matching, case analysis, and systems of linear inequalities; metaprogramming lets users add notation and proof automation. Projects are managed with Lake, the package manager bundled with Lean. Mathlib is a community-driven library with over a million lines spanning areas including algebra, analysis, topology, probability, and computer science. The recommended setup uses VS Code with the Lean 4 extension for syntax highlighting and code completion, while Neovim with lean.nvim is also well-supported. Lean runs on Linux, macOS, and Windows, and Lean4Web lets users run code in a browser. The software is free under the Apache 2.0 license. Learning resources include textbooks, tutorials, interactive games, documentation, and an API reference.