Rex AST (rex-ast)

This crate defines the core syntax tree for Rex and shared language data types.

What’s here

• rex_ast: expression/decl/type AST nodes (CompilationUnit, Expr, Decl, TypeExpr, etc.)
• Symbol + interning utilities (intern): stable identifiers used across crates
• Span/Position source ranges so diagnostics can point at source locations

This crate is intentionally “dumb”: it’s primarily data structures and small helpers, used by the parser, type system, engine, and tooling.