Module ast 

The abstract syntax tree: the typed shape a .vrf source parses into.

Everything here is zero-copy over the source &str (atoms/names borrow their slices) and every node that can be pointed at in an error carries its Span via Located.

Structs

Atom

An atom is the triple (subject, predicate, object?) — the unit of identity — optionally qualified by a domain (physics.engine has fuel). Creature_A has flying and Creature_A has swimming are DIFFERENT atoms.

Literal

A literal is an atom, optionally negated (NOT ...).

Located

Container for data associated with its source location.

Program

A parsed program: a flat sequence of statements.

Enums

Body

The body of an PREMISE or RULE.

Conn

How the literals in a WHEN/THEN group combine. A single-literal group is always Conn::And (the connective is irrelevant with one literal).

ListOp

List constraint operators (body of a list-style PREMISE).

Statement

A top-level statement.

Type Aliases

Span

Source code fragment with line and column tracking.