Typecheck

Reusable typeCheck handlers: strict (throw), collecting (accumulate), logging (record all).

collecting

Collecting typeCheck handler: accumulates errors in state. Resumes with true on success, false on failure (computation continues).

State shape: list of { context, typeName, actual, message } Initial state: []

logging

Logging typeCheck handler: records every check (pass or fail) in state. Always resumes with the actual check result (boolean).

State shape: list of { context, typeName, passed } Initial state: []

strict

Strict typeCheck handler: throws on first type error. Resumes with true on success (check passed).

Use when type errors should halt evaluation immediately. State: unused (pass null).