Spec Update: Batch 07 — Type Definitions, Enums, Tags

Date: 2026-04-16 Plans Referenced: Plan 019 (specs), Plan 021 (enums), Plan 035 (static methods), Plan 048 (generics), Plan 057 (generic specs), Plan 059 (ext blocks), Plan 163 (pub) Source Files: ast/types.rs (TypeDecl, GenericParam), ast/enums.rs (EnumDecl, EnumKind), ast/ext.rs (Ext) Sections Updated: Type Definitions (Section 11), Enums (Section 12 — NEW), Unions and Tags → merged into Enums

Old Content

Type Definitions

• "Type Modifiers" section with postfix syntax: int[], int*, int&, int?
• Basic type Point { x int, y int } definitions
• Type aliases with alias

Unions and Tags

• C-style unions and tagged unions in one section
• Tags pattern matching used -> (incorrect)

New Content

Type Definitions (rewritten)

• Removed old "Type Modifiers" section (postfix syntax now documented in Types section)
• Added single inheritance: type Dog is Animal { ... }
• Added generic types: type Container<T>, const generics type Inline<T, N u32>
• Added spec implementation: type X has SpecY
• Added ext blocks: ext str { fn method() { ... } }
• Added TypeDecl fields table (internal reference)
• Fixed constructor syntax: Point(10, 20) not { x: 10, y: 20 }

Enums (NEW section)

• Three enum kinds: Scalar, Homogeneous, Heterogeneous (ADT)
• Scalar with repr type: enum HttpStatus u16 { OK = 200 }
• Generic enums: enum Option<T>, enum Result<T, E>
• EnumDecl fields table
• Tags moved here as a subsection
• Fixed pattern matching arrow: -> → =>

Notes

• Old "Unions and Tags" section replaced by new Enums section (Section 12)
• C-style unions (union MyUnion { ... }) still documented but de-emphasized
• Tags are a subset of the enum system (tagged unions)