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The Petr4 project is developing the formal semantics of the P4 Language backed by an independent reference implementation.

POPL'21 artifact

See or check out the gh-pages branch for information on the Petr4 artifact.

Getting Started

Installing Petr4

  1. Install OPAM 2 following the official OPAM installation instructions. Make sure opam --version reports version 2 or later.

  2. Install external dependencies:

    sudo apt-get install m4 libgmp-dev

Installing from OPAM

  1. Install petr4 from the opam repository. This will take a while the first time because it installs OPAM dependencies.
    opam install petr4

Installing from source

You can use the scripts to install Petr4. Alternatively, follow theses steps:

  1. Check the installed version of OCaml:

    ocamlc -v

    If the version is less than 4.09.1, upgrade:

    opam switch 4.09.1
  2. Install p4pp from source.

  3. Use OPAM to install dependencies.

    opam install . --deps-only

    If this doesn't work, install the dependencies manually.

    opam install ANSITerminal alcotest bignum cstruct-sexp pp ppx_deriving ppx_deriving_yojson yojson js_of_ocaml js_of_ocaml-lwt js_of_ocaml-ppx
  4. Build binaries using the supplied Makefile

  5. Install binaries in local OPAM directory

    make install
  6. [Optional] Run tests

    make test

Running Petr4

Currently petr4 is merely a P4 front-end. By default, it will parse a source program to an abstract syntax tree and print it out, either as P4 or encoded into JSON.

Run petr4 -help to see the list of currently-supported options.

Web user interface

petr4 uses js_of_ocaml to provide a web interface. To compile to javascript, run make web. Then open index.html in html_build in a browser.


Petr4 is an open-source project. We encourage contributions! Please file issues on Github.


See the list of contributors.


Petr4 is released under the Apache2 License.