Foundation course

A complete introduction to L4. It assumes basic familiarity with legal concepts and no programming experience.

The course takes you from zero to modelling a small legal scheme. You will learn to write legal rules that a computer can check and run, model legal entities and their relationships, express multi-step legal processes, and test them against scenarios. Take the modules in order; each builds on the ones before.

Modules

• Module 0: Introduction to L4: what L4 is for, the parts of an L4 file, and setting up.
• Module 1: Your first legal rule: an obligation with PARTY and MUST, a condition, a deadline and consequences.
• Module 2: Legal entities and relationships: records and enumerations with DECLARE, and field access.
• Module 3: Control flow: IF, BRANCH, CONSIDER, boolean logic and lists.
• Module 4: Decision logic: constitutive rules with DECIDE and MEANS, signatures, WHERE, MAYBE and dates.
• Module 5: Functions: calling functions, recursion, and higher-order functions such as map and filter.
• Module 6: Regulative rules: obligations, permissions and prohibitions, chained with HENCE and LEST and tested with #TRACE.
• Module 7: Putting it together: a complete model of a charity registration scheme.

After this course

Continue with the Advanced course. For a specific task, see the Tutorials; to look up a keyword, the Reference; for why L4 works as it does, Concepts. Report a problem on GitHub.