XPOP: a meta-language without metaphysics

Abstract

The XPOP programming system is a straightforward and practical means of implementing on a computer a great variety of languages---in other words, of writing a variety of compilers. The class of languages it can handle is not easy to characterize by syntactic form, since the system permits syntax specification to be varied freely from statement to statement in a program being scanned; the permitted class includes the best-known programming languages, as well as something closely approaching natural language. We believe that this distinguishes the XPOP processor from the syntax-directed compilers, although it shares with them the fundamental idea that the process of programming-language translation can be usefully generalized by a compiler to which source-language syntax is specified as a parameter.