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https://github.com/CatalaLang/catala

Programming language for literate programming law specification
https://github.com/CatalaLang/catala

legislative-texts programming-language

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Programming language for literate programming law specification

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README 

        


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	Catala

  


  


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![CI][ci-link] [![Opam][opam-link]](https://opam.ocaml.org/packages/catala/) [![Licence][licence-link]](https://www.apache.org/licenses/LICENSE-2.0) ![Tag][tag-link] ![LoC][loc-link] ![Language][language-link] [![Issues][issues-link]](https://github.com/CatalaLang/catala/issues) [![Contributors][contributors-link]](https://github.com/CatalaLang/catala/graphs/contributors) [![Activity][activity-link]](https://github.com/CatalaLang/catala/pulse)



Catala is a domain-specific language for deriving

faithful-by-construction algorithms from legislative texts. To learn quickly

about the language and its features, you can jump right to the official

[Catala tutorial](https://catala-lang.org/en/examples/tutorial).

You can join the Catala community on [Zulip][chat-link]!










  Table of Contents



* [Concepts](#concepts)

* [Getting started](#getting-started)

* [Building and installation](#building-and-installation)

* [Usage](#usage)

  * [Catala](#catala)

  * [Clerk](#clerk)

* [Documentation](#documentation)

  * [Syntax cheat sheet](#syntax-cheat-sheet)

  * [Formal semantics](#formal-semantics)

  * [Compiler documentation](#compiler-documentation)

* [Examples](#examples)

* [API](#api)

* [Contributing](#contributing)

* [Test suite](#test-suite)

* [License](#license)

* [Limitations and disclaimer](#limitations-and-disclaimer)

* [Pierre Catala](#pierre-catala)



## Concepts



Catala is a programming language adapted for socio-fiscal legislative literate

programming. By annotating each line of the legislative text with its meaning

in terms of code, one can derive an implementation of complex socio-fiscal

mechanisms that enjoys a high level of assurance regarding the code-law

faithfulness.



Concretely, you have to first gather all the laws, executive orders, previous

cases, etc. that contain information about the socio-fiscal mechanism that

you want to implement. Then, you can proceed to annotate the text article by

article, in your favorite text editor :





Screenshot




Once your code is complete and tested, you can use the Catala

compiler to produce a lawyer-readable PDF version of your

implementation. The Catala language has been specially designed

in collaboration with law professionals to ensure that the code

can be reviewed and certified correct by the domain experts, which

are in this case lawyers and not programmers.





Screenshot




The Catala language is special because its logical structure mimics

the logical structure of the law. Indeed, the core concept of

"definition-under-conditions" that builds on default logic has been formalized

by Professor Sarah Lawsky in her article

[A Logic for Statutes](https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3088206).

The Catala language is the only programming language to our knowledge that

embeds default logic as a first-class feature, which is why it is the only

language perfectly adapted to literate legislative programming.



## Getting started



To get started, the best place is the [tutorial](https://catala-lang.org/en/examples/tutorial)

of the language. A [French version](https://catala-lang.org/fr/examples/tutoriel)

is also available but might be out of sync with the latest language features.



> **Note:** bleeding-edge version

>

> If you are interested in the latest development version, pre-built artifacts

> including binaries and API documentation can be found at

> https://catalalang.github.io/catala



## Building and installation



Catala is available as an [opam package](https://opam.ocaml.org/packages/catala/)!

If opam is installed on your machine, simply execute:



    opam install catala



To get the cutting-edge, latest version of Catala, you

can also do



    opam pin add catala --dev-repo



However, if you wish to get the latest developments of the compiler, you probably

want to compile it from the sources of this repository or use nix. For that, see

[the dedicated readme](INSTALL.md).



## Usage



### Catala



Use `catala --help` if you have installed it to get more information about the

command line options available. The man page is also [available

online](https://catala-lang.org/en/doc/catala). To get the development version

of the help, run `make help_catala` after `make build`. The `catala` binary

corresponds to the Catala compiler.



The top-level `Makefile` contains a lot of useful targets to run. To display

them, use



        make help



### Plugin backends



While the compiler has some builtin backends for Catala (Python, Ocaml, etc.),

it is also possible to add a custom backend to the Catala compiler without

having to modify its source code. This plugin solution relies on dynamic

linking: see [the dedicated README](compiler/plugins/README.md).



### Clerk



Use `clerk --help` if you have installed it to get more information about the

command line options available. To get the development version of the help, run

`make help_clerk` after `make build`. The `clerk` binary corresponds to the

Catala build system, responsible for testing among other things.



To get more information about Clerk, see [the dedicated readme](https://github.com/CatalaLang/catala/tree/master/build_system/README.md)



### Catleg



Catleg is a command line utility providing useful integration with

[LégiFrance](https://legifrance.gouv.fr), the official repository of French

legal documentation. See the [decidated

repository](https://github.com/catalaLang/catleg) for more information.



## Documentation



### Syntax cheat sheet



A complete and handy reference of the Catala syntax can be found in the [cheat

sheet](https://catalalang.github.io/catala/syntax.pdf) (for French and English

versions of the syntax).



### Formal semantics



To audit the formal proof of the partial certification of the Catala compiler,

see [the dedicated readme](doc/formalization/README.md).



### Compiler documentation



The documentation is accessible online, both for the [latest release](https://catala-lang.org/ocaml_docs/) and [bleeding-edge version](https://catalalang.github.io/catala/api-doc/).



It is otherwise generated from the compiler source code using

`dune` and `odoc`. Run



    make doc



to generate the documentation, then open the `doc/odoc.html` file in any browser.



## Examples



To explore the different programs written in Catala, see [the dedicated

readme](https://github.com/CatalaLang/catala-examples/blob/master/README.md).



## API



To know how to use the code generated by the Catala compiler in your favorite

programming language, head to the [readme of the French law

library](https://github.com/CatalaLang/french-law/blob/master/README.md). The

corresponding pre-built examples are also

[available](https://catalalang.github.io/catala/).



## Contributing



To know how you can contribute to the project, see

[the dedicated readme](CONTRIBUTING.md).



## Test suite



To know how to run or improve the Catala reference test suite,

see [the dedicated readme](tests/README.md).



## License



The compiler and all the code contained in this repository is released under

the [Apache license (version 2)](LICENSE.txt) unless another license is explicited

for a sub-directory.



## Limitations and disclaimer



Catala is a research project from Inria, the French National

Research Institute for Computer Science. The compiler is yet

unstable and lacks some of its features.



## 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.



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[chat-link]: https://zulip.catala-lang.org/

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[licence-link]: https://img.shields.io/github/license/catalalang/catala

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[loc-link]: https://img.shields.io/tokei/lines/github/catalalang/catala

[issues-link]: https://img.shields.io/github/issues/catalalang/catala

[opam-link]: https://img.shields.io/badge/Package-opam-orange?logo=OCaml&link=https://opam.ocaml.org/packages/catala/

[language-link]: https://img.shields.io/github/languages/top/catalalang/catala

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