Abstract: Multiple software facilities are described. A property mapping facility enables a programming language compiler to map properties defined according to one property accessor style to another property accessor style. A reference mapping facility enables a programming language compiler to emit instructions that cause a parameter to a method to be provided by reference even when the programming language does not support providing parameters by reference. A type extension facility enables a programming language compiler to extend the number of declarative type modifiers that the compiler supports. A partial class facility enables a programming language compiler to postpone compiling a class marked as partial until the compiler can compile the entire class. A value type facility enables a programming language compiler to recognize “value data types” that offer advantages of both reference data types and primitive data types.