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Abstractions

• Definition mechanism.
• Invocation mechanism.
• Abstract = name plus body
  • Body expression from syntax domain B.
  • Abstract can be invoked by using its name any place where a B expression is (syntactically) legal.
• Examples:
  • Command abstracts (procedures).
  • Expression abstracts (functions, constants).
  • Declaration abstracts (classes, modules).
  • Type abstracts (named types).

Any syntax domain of a language may have definition and invocation mechanisms for abstracts.