Section: Software and Platforms

Tool support for the working semanticist

Participant : Francesco Zappa Nardelli [contact] .

Languages, semantics, tool support, theorem prouvers.

We are working on tools to support large scale semantic definitions, for programming languages and architecture specifications. For that we develop two complementary tools, Ott and Lem.

Ott is a tool for writing definitions of programming languages and calculi. It takes as input a definition of a language syntax and semantics, in a concise and readable ASCII notation that is close to what one would write in informal mathematics. It generates output:

1. a LaTeX source file that defines commands to build a typeset version of the definition;

2. a Coq version of the definition;

3. an Isabelle version of the definition; and

4. a HOL version of the definition.

Additionally, it can be run as a filter, taking a LaTeX/Coq/Isabelle/HOL source file with embedded (symbolic) terms of the defined language, parsing them and replacing them by typeset terms.

The main goal of the Ott tool is to support work on large programming language definitions, where the scale makes it hard to keep a definition internally consistent, and to keep a tight correspondence between a definition and implementations. We also wish to ease rapid prototyping work with smaller calculi, and to make it easier to exchange definitions and definition fragments between groups. The theorem-prover backends should enable a smooth transition between use of informal and formal mathematics.

Lem is a lightweight tool for writing, managing, and publishing large scale semantic definitions. It is also intended as an intermediate language for generating definitions from domain-specific tools, and for porting definitions between interactive theorem proving systems (such as Coq, HOL4, and Isabelle). As such it is a complementary tool to Ott. Lem resembles a pure subset of Objective Caml, supporting typical functional programming constructs, including top-level parametric polymorphism, datatypes, records, higher-order functions, and pattern matching. It also supports common logical mechanisms including list and set comprehensions, universal and existential quantifiers, and inductively defined relations. From this, Lem generates OCaml, HOL4, Coq, and Isabelle code.

In collaboration with Peter Sewell (Cambridge University) and Scott Owens (University of Kent).

The current version of Ott is about 30000 lines of OCaml. The tool is available from http://moscova.inria.fr/~zappa/software/ott (BSD licence). It is widely used in the scientific community. In 2013 we implemented several bug-fixes, we kept the theorem prouver backends up-to date with the prover evolution, and we have been working toward a closer integration with the Lem tool.

The development version of Lem is available from http://www.cs.kent.ac.uk/people/staff/sao/lem/ .