Books / Law as Code in Practice: French Family Benefits / Appendix F
Appendix F
Where Catala and OpenFisca Stand
Contents of Law as Code in Practice: French Family Benefits
Most chapters close with a short section on how Catala — and, in some chapters, OpenFisca or L4 — meets the same need. Those sections describe the other tools as their own documentation presents them. They were checked against Catala 1.3.0 (released 1 October 2026) and the Catala book on 11 October 2026; the date is printed here once instead of under every section. The Catala book is published by its authors under the Creative Commons Attribution 4.0 licence; these sections link to it and summarise it in their own words, without reproducing its text.
Tools change. If something has changed, tell us at hi@arxo.io. Corrections are published with the next edition and listed under Corrections.
| Chapter | What the chapter compares |
|---|---|
| 0 | the distinctions the book adds: missing facts, contradictions, judgments, readings, rounding, duties and pinned sources |
| 1 | source anchors and pinned publications behind a dated answer |
| 2 | a missing fact: optional values against a truth status and a why_not question |
| 3 | parameter rows with validity windows and source anchors |
| 4 | the decision around the amount: duties and the chosen rounding reading |
| 5 | scenario tests, and a check that names the missing premise |
| 6 | a statutory formula and the pinned publication behind it |
| 7 | a division the text does not round: cent conversion against a named reading |
| 8 | competing constructions: inputs or scopes against named readings with a required choice |
| 9 | a judgment reserved for a named authority, and the duties and immunity that follow |
| 10 | duties and their assessment states, with L4’s obligations and outcomes |
| 11 | dated payment checkpoints with their duties and recovery grounds |
| 12 | procedural positions and an argument graph for a contested recovery |
| 13 | computation traces against a fingerprinted document attached to the case |
| 14 | reform simulation in OpenFisca against a draft check and an impact report |
| 15 | population simulation against screening on a necessary condition |
| 16 | an assistant’s answer with its saved proof graph, and MCP in L4 |
| 17 | computation traces against replay by programme, case and result fingerprints |
| 18 | migrating external tests with their original expectations |
| Final exercise | a draft amendment: OpenFisca’s reform mechanism against draft check, evaluation and impact |