ACL2

ACL2 is a comprehensive programming language, specification language, modeling language, formal mathematical logic, and semi-automatic theorem prover.

ACL2 is both a programming language in which you can model computer systems and a tool to help you prove properties of those models. ACL2 is a very large, multipurpose system. You can use it as a programming language, a specification language, a modeling language, a formal mathematical logic, or a semi-automatic theorem prover, just to name its most common uses.