ACL2 vs Why3
ACL2
acl2.orgWhy3
why3.orgSide by side
| Figure | ACL2 | Why3 |
|---|---|---|
| Price from | — | Free |
| Free plan | — | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | — | Yes |
| Windows | Yes | Yes |
| macOS | Yes | — |
| Linux | Yes | Yes |
| API | — | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 0 | 1 |
| Spec score · Formal Verification Tools | 7.8 (#14) | 8.0 (#12) |
| Installation | Unix-like installation instructions cover Linux, macOS with Intel or ARM processors, and FreeBSD; Windows has separate installation instructions. | Why3 can be installed via Opam, run from a Docker image, or compiled from source. |
| Integrations | The Community Books include interfacing tools for file I/O, operating-system access, raw Common Lisp libraries, and connections to other programs. | The project lists EasyCrypt, Frama-C, and SPARK 2014 among projects that use Why3. |
| Purpose | ACL2 combines a Lisp-based programming language for formal models with a reasoning engine that can prove properties about those models. | Why3 is a platform for deductive program verification that uses WhyML and external theorem provers to discharge verification conditions. |
| Support | ACL2 users can get help through the acl2-help mailing list, which the site recommends to new users. | The project provides a user mailing list, a Zulip chat, and a bug tracking system. |
Plans
In their own words
Why3
Why3 is a platform for deductive program verification. It uses WhyML to express programs and specifications, then works with external automated or interactive theorem provers to discharge verification conditions. WhyML supports preconditions, postconditions, assertions, and loop invariants, alongside logical theories and data structures such as arrays, queues, and hash tables. External provers need to be installed and configured separately. Why3 can be extended with support for new provers and used as a software library through its OCaml API. WhyML programs can be extracted automatically into correct-by-construction OCaml programs, and WhyML is also used as an intermediate language for verification of C, Java, Rust, and Ada. TryWhy3 provides a JavaScript version that runs in a browser. Installation options include Opam, Docker, source compilation, and listed Debian, Fedora, and Ubuntu packages. Its graphical interface saves proof attempts and transformations in an XML file and can replay obsolete attempts. Why3 is free and open source under GNU LGPL 2.1 with a special linking exception. Loop invariant inference is a work in progress, and many features remain very limited.