CFML : a framework for interactive proofs of ML programs in Separation Logic

CFML is for carrying out proofs of correctness of OCaml programs with respect to specifications expressed in higher-order Separation Logic.

CFML consists of two main parts:

• A front-end tool, implemented in OCaml, parses OCaml source code and translates it to an abstract syntax tree inside Coq.

• A Coq library provides definitions, lemmas, a characteristic formula generator, and a suite of tactics, which make it possible to reason in Coq about an OCaml program.

Installation

CFML uses OCaml version < 5 (it has not been tested with multicore OCaml). CFML has been tested with Coq v8.18.

To install OCaml, Coq, and the relevant packages, use the "opam" package manager.

   # If you have never used opam before
   opam init

To create a new switch to contain the relevant packages for cfml:

   opam switch create 4.14.1

To install the packages:

   opam install pprint coq menhir 

To install the TLC opam package from sources:

   cd ~
   git clone git@github.com:charguer/tlc.git
   cd tlc/src
   make -j4 && make install

To obtain CFML sources and compile them:

  cd ~
  git clone https://gitlab.inria.fr/charguer/cfml2.git
  cd cfml2
  make depend
  make -j8 all

To install the VsCoq IDE for Coq embedded in VScode, follow this tutorial: https://chargueraud.org/teach/verif/install/install.html In particular, this tutorial suggests a set of alternative key-binding.

Starting with the tutorial

If make all succeeds, you can open the root folder of "cfml2" into VScode (or another IDE), and play the files interactively.

  code . &

To begin with open the tutorial, type 'ctrl+p' then 'Tutorial_proof.v'. If every thing goes well, you should be navigate through the file like in any other Coq file. (Type 'ctrl+shift+p' then 'Coq' to see the shortcuts.)

Contributing your own formalization

Copy the folder 'examples/tutorial' into 'examples/mydev'. Rename the file, and commit the files into a git branch of your own. Then, type "make" to compile the files located in your new folder. Open these files in your IDE just like those from the tutorial.

Documentation

The file CHEATSHEET.md provides a summary of the tactics and notation.

The file lib/coq/WPTactics.v contains the detailed documentation for all the tactics.

The file generator/README.md contains documentation for the characteristic formula generator.

The construction of CFML 2.0 is described in this manuscript: https://www.chargueraud.org/research/2023/hdr/chargueraud-hdr.pdf

Besides, the core of CFML 2.0 is described in the all-in-Coq course: Foundations of Separation Logic

Examples

The 'examples' folder contains tutorials, case studies, and unit tests.

Tutorials

• examples/Tutorial/Tutorial.v contains a short tutorial

Case studies

• examples/Stack: verification of a stack implemented as a reference on a list---a simple yet very illustrative example.
• examples/MList: verification of simple operations on a mutable list; includes specifications where the list "owns" its elements.
• examples/PairingHeap: verification of imperative pairing heaps; a heap is represented as a tree of variable arity; concretely, each tree consists of a mutable list of mutable subtrees.

Unit tests:

• examples/UnitTests contains unit tests covering all language constructs
• examples/UnitTestsCredits contains unit tests for the 'xpay' tactics, for reasoning about asymptotic complexity about the code.