Language¶

The Fourier language reference. Each page below covers one construct, grounded in fourier/parser.py and fourier/codegen.py.

Recommended reading order for new readers:

1. Contracts — the top-level contract { ... } block. What goes inside and the init function.
2. Types — uint, address, bool, bytes, plus map[K, V] and array[T] for storage.
3. Storage — storage NAME: TYPE @ SLOT; declarations and how slots are derived for mappings, arrays, and struct fields.
4. Functions — fn vs pub fn, selector assignment, parameters, return types.
5. Statements — let, assignment, if, while, return, require, emit.
6. Expressions — operators, precedence, builtins.
7. Events — event declarations, emit semantics, topic vs data layout.
8. Errors and reverts — how require revertss, how sub-call failures propagate, the optional bytes revert payload.
9. Cross-contract calls — call_b, delegatecall_b, staticcall_b, and the one-word call.
10. Address type — semantics, sentinels, comparison rules, builtins that return addresses.

The full grammar lives at fourier/GRAMMAR.md in the repo. This reference is its more detailed, code-grounded companion.