Module ast 

AST infrastructure types

This module contains metadata types used throughout the parser and compiler:

• Span for tracking source code locations
• ExpressionId for uniquely identifying AST nodes
• ExpressionIdGenerator for generating unique IDs during parsing

Structs

ExpressionId

Unique identifier for each expression in the AST

ExpressionIdGenerator

Counter for generating unique expression IDs

Span

Span representing a location in source code