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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] ![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://book.catala-lang.org/2-0-tutorial.html).

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










  Table of Contents



* [Concepts](#concepts)

* [The Catala book](#the-catala-book)

* [IDE Extensions and Tooling](#ide-extensions-and-tooling)

  * [Syntax highlighting](#syntax-highlighting)

  * [Catala VScode extension](#catala-vscode-extension)

  * [Code formatting](#code-formatting)

* [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.



## The Catala Book



The one-stop-shop for tutorials, installation instructions, FAQ and reference

guide about Catala is the [Catala book](https://book.catala-lang.org) available

at:





https://book.catala-lang.org




## IDE Extensions and Tooling



### Syntax highlighting



Syntax highlighting is available for several text-editors. Scripts can

be found

[here](https://github.com/CatalaLang/catala/tree/master/syntax_highlighting).



### Catala VSCode Extension



A VSCode extension for Catala is available [on the

marketplace](https://marketplace.visualstudio.com/items?itemName=catalalang.catala).

It bundles a syntax highlighter and a dedicated LSP server which

offers support for code navigation, auto-completion along with a UX

for test suites. See the [dedicated

repository](https://github.com/catalaLang/catala-language-server) for

more details.



### Code formatting



A code formatting tool, `catala-format` is available alongside the LSP

server. If installed, code formatting is directly available in VSCode.

This tool is based on a [`tree-sitter`

grammar](https://github.com/CatalaLang/tree-sitter-catala) for

Catala. See the [dedicated

repository](https://github.com/catalaLang/catala-format) for more

details.



## Additional documentation items



### 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.



[chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg?style=social&logo=zulip&color=5c75a2

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

[ci-link]: https://github.com/catalalang/catala/actions/workflows/harness.yml/badge.svg

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

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

[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

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

[activity-link]: https://img.shields.io/github/commit-activity/m/catalalang/catala