- Resolve types for all identifiers.
- Error when identifier is not found.
- Match return type and error when not returning a value when it should.
- Check unreachable code (code after sure return).
- Match argument count and types for function calls.
- Determine if return type of function call matches the assignment.
- Do static type check with match statement when possible.
- Use type hints to determine export type.
- Check compatibility between type hint and explicit export type.