IR

Tsonic’s IR is the frontend/backend boundary.

What IR Captures

• module identity
• imports/exports
• statements
• expressions
• resolved types
• generic substitutions
• backend-relevant semantic decisions that must survive into emission

What IR Does Not Try To Be

• it is not a backend syntax tree
• it is not raw TypeScript AST
• it is not Roslyn AST

The backend syntax tree is a later layer: CSharpAst.

Why This Split Exists

IR keeps frontend reasoning separate from backend syntax concerns.

Examples:

• source-package resolution belongs in the frontend/IR side
• C# keyword escaping belongs in the backend AST/printer side
• numeric proof belongs before backend emission

Current Pressure Points Captured in IR

• nameof / sizeof
• Promise chain normalization
• dynamic import normalization
• object-literal method/accessor lowering intent
• generic function value specialization state