tabareau/coq-malfunction

Verified Extraction from Coq to OCaml

This repository contains the current development state of a new verified extraction from Coq to OCaml, based on MetaCoq. Technically, the extraction targets Malfunction, which is a specification of Lambda, the internal language of the OCaml compiler. We use Malfunction as target for extraction from Coq, and rely on the Malfunction and OCaml compilers to obtain .cmx files that will behave like .cmx files created by Coq's current extraction process and the Ocaml compiler. In particular, Coq programs extracted like this can interact with other OCaml programs and with Coq programs extracted using the existing extraction.

The implementation of extraction is fully functional and supports primitive integers and floats, but no cofixpoints yet. Verification is work in progress.

Installation

opam switch create coq-malfunction --packages="ocaml-variants.4.13.1+options,ocaml-option-flambda"
eval $(opam env --switch=coq-malfunction)
opam repo add coq-released https://coq.inria.fr/opam/released
opam pin -n -y "https://github.com/MetaCoq/metacoq.git#b33a9bd"
opam pin -n -y "https://github.com/yforster/malfunction.git#for-pack"
opam install . --deps-only
make -j 4

Usage

After From VerifiedExtraction Require Import Loader. the commands MetaCoq Verified Extraction <definition> and MetaCoq Verified Extraction <definition> "<file>.mlf" can be used to run the new extraction process. To add an mli file one can add the output of the (unverified) generator MetaCoq Run Print mli <definition>. to a .mli file.

Structure

• Malfunction.v contains the syntax definition of Malfunction. It is a direct, line-to-line port of the OCaml file malfunction.ml to Coq.
• SemanticsSpec.v defines an inductive big-step evaluation predicate.
• Compile.v defines a compilation function of lambda box to Malfunction.
• CompileCorrect.v proves the correctness of this function, using the correctness proof of case analysis in Mcase.v
• Interpreter.v contains an interpretation function, which is close to malfunction_interpreter.ml, and a proof that values according to the evaluation predicate are also found by the interpreter. Note that since the interpreter is not necessarily terminating we switch of Coq's termination checker, meaning this proof can only be seen as a sanity check.
• Serialize.v contains seralization functions into s-expressions. There is also a parser in Deserialize.v, used for testing.
• Pipeline.v composes the full extraction pipeline from Coq to Malfunction

Team & Credits

The project is developed by Yannick Forster, Matthieu Sozeau, Pierre-Marie Pédrot, and Nicolas Tabareau.

Copyright (c) 2022--2023 Yannick Forster, Matthieu Sozeau, Nicolas Tabareau