HOL Light vs Why3
HOL Light
hol-light.github.ioWhy3
why3.orgSide by side
| Figure | HOL Light | Why3 |
|---|---|---|
| Price from | — | Free |
| Free plan | — | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | Yes | Yes |
| macOS | Yes | — |
| Linux | Yes | Yes |
| API | — | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 0 | 1 |
| Spec score · Formal Verification Tools | 7.5 (#21) | 8.0 (#12) |
| Browser access | The official site links to a browser version that runs HOL Light in a web browser. | TryWhy3 is a JavaScript version of the Why3 Verification Platform that runs in a browser. |
| Extensibility | HOL Light is fully programmable, allowing users to extend it with new theorems and inference rules without compromising soundness. | Why3 can be extended with support for new external provers and used as a software library through its API. |
| Installation | The official installation instructions recommend installing HOL Light through OPAM or cloning its GitHub source repository. | Why3 can be installed via Opam, run from a Docker image, or compiled from source. |
| Purpose | HOL Light is a computer program for formally proving mathematical theorems in higher-order logic. | Why3 is a platform for deductive program verification that uses WhyML and external theorem provers to discharge verification conditions. |
Plans
In their own words
HOL Light
HOL Light has no write-up on Specifiction yet; its figures are above.
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.