2 Rational

This section can be skipped by a user that only wants to use AS. However, it will help to understand the reasons why the AS formalism has been created and the choices that have been made in its design.

• 2.1 The Computer Languages Factory
• 2.2 Abstract Syntax
• 2.3 Isolating Abstract Syntax from Concrete Syntax
• 2.4 Modularity
• 2.5 Second-Order Abstract Syntax