3.9 KiB
Catala
Catala is a domain-specific language for deriving faithful-by-construction algorithms from legislative texts.
OCaml requirements
The Catala compiler is written using OCaml. To install OCaml on your machine and if you're running Linux ou MacOS, open a terminal and enter :
./install_opam.sh
This will install opam, the OCaml dependency manager and the base OCaml compiler.
Next, install all the build dependencies with
make install-dependencies
This should ensure everything is set up for developping on Catala !
The Catala compiler
Installation
The project is distributed as a Dune artifact. Use standard dune commands to build and install the library. In particular, if you want to install the library as an opam package, use the following command at the root of the repository:
opam install ./
You can then can the compiler using the catala command.
Usage
Use catala --help to get more information about the command line options available.
Syntax highlighting
The Catala language also comes with syntax highlighting to ease program development. The syntax highlighting is done with the Iro compiler that allows writing the syntax only once, and then export it to formats understood by various IDE. Currently, two syntax highlighting plugins are under version control.
Atom
To get Catala syntax highlighting in Atom, simply enter from the root of the repository :
ln -s -f $(pwd)/syntax_highlighting/atom ~/.atom/packages
You can now reload Atom and check that you have syntax highlighting on any .catala file.
Pygments
Pygments is a Python-based versatile lexer for various
programming languages. To use a version of Pygments
augmented with the Catala plugin, you need to execute the
script syntax_highlighting/pygments/set_up_pygments.sh
This script assumes a python3 executable on tour machine,
as well as the virtualenv package which you can install
using python3 -m pip install virtualenv .
The scripts sets up a virtual environement in syntax_highlighting/pygments/pygments/env, which will
contain the modified version of Pygments that has Catala
support. You can use this virtual environnement with
source syntax_highlighting/pygments/pygments/env/bin/activate
The pigmentize executable, used for instance by the minted LaTeX package,
will now point to the Catala-enabled version inside the virtual environment.
Catala motivating example : French "allocations familiales"
In the example/allocations_familiales folder, you will find the
allocations_familiales.catala file which contains the
algorithm computing French family benefits. The algorithm consists of annotations to the legislative
texts that define the family benetifs, using the literate programming paradigm. The catala
compiler can extract from the .catala file a lawyer-readable version of the annotated text.
Currently, this lawyer-readable version comes in the form of a LaTeX document.
You will need to have a standard LaTeX distribution installed as well as the
latexmk build tool in order to enjoy the automated document generation process.
To get that lawyer-readable version (which is a LaTeX-created) PDF, simply use
make allocations_familiales
from the repository root. You can then open examples/allocations_familiales/allocations_familiales.pdf
License
The library is released under the Apache license (version 2).
Pierre Catala
The language is named after Pierre Catala, a professor of law who pionneered the French legaltech by creating a computer database of law cases, Juris-Data. The research group that he led in the late 1960s, the Centre d’études et de traitement de l’information juridique (CETIJ), has also influenced the creation by state conselor Lucien Mehl of the Centre de recherches et développement en informatique juridique (CENIJ), which eventually transformed into the entity managing the LegiFrance website, acting as the public service of legislative documentation.