Participants

• Function (FUNCTION)
  • declares an interface for function application. Its two type parameters specify argument and result type respectively³.
  • is used as the interface specification for both generic and specialized functions.
• Generic function (GEN_FUNC)
  • corresponds to a denotational function definition.
  • uses function package FUNCTIONS and run time type information to choose and then delegate to a specialized function.
• Specialized function (e.g., PF_IF)
  • corresponds to one pattern matching branch of a denotational function definition.
  • defines a local transformation for a source element (e.g., TY_IF) to a corresponding target element (e.g., PP_IF).
  • recursively transforms subcomponents of its argument as well.
• Function package (e.g., FUNCTIONS)
  • conceptually bundles related specialized functions.
  • declares a generic type for specialized functions to be refined by concrete function packages.
• Concrete Function package (e.g., PP_FUNCTIONS)
  • defines a mapping from source elements to their corresponding specialized functions.
  • creates prototypes of -- and then aggregates -- specialized functions.
• Client
  • creates or uses a source structure (e.g., TOY_LANG).
  • initializes or uses a function package (e.g., PP_FUNCTIONS).
  • creates or uses a generic function (GEN_FUNC).
  • applies a generic function to a source structure.