Syntax extension and the IMP72 programming language
Walter Bilofsky · ACM SIGPLAN Notices · 1974
The IMP72 language for the DEC PDP-10 computer is the most recent of the IMP family of extensible software implementation languages. Its facility for extending the syntax of the language, the syntax statement, is simple enough to be useful to relatively unsophisticated users, yet powerful enough that the IMP72 language is defined by an IMP72 source program consisting of syntax statements.