@article {18397,
	title = {Implementation of language enhancements},
	journal = {Computer Languages},
	volume = {6},
	year = {1981},
	month = {1981///},
	pages = {139 - 153},
	abstract = {Data abstractions have been proposed as a means to enhance program modularity. The implementation of such new features to an existing language is typically handled by either rewriting large portions of an existing compiler or by using a preprocessor to translate the extensions into the standard language. The first technique is expensive to implement while the latter is usually slow and clumsy to use. In this paper a data abstraction addition to PL 1 is described and a hybrid implementation is given. A minimal set of primitive features are added to the compiler and the other extensions are added via an internal macro processor that expands the new syntax into the existing language.},
	keywords = {Compiler design, Data abstraction, Language extensions, specifications},
	isbn = {0096-0551},
	doi = {10.1016/0096-0551(81)90026-6},
	url = {http://www.sciencedirect.com/science/article/pii/0096055181900266},
	author = {Zelkowitz, Marvin V and Lyle,James R.}
}
