A short presentation of the main features of AEPL - an extensible programming language
JACOB KATZENELSON, E. Milgrom · ACM SIGPLAN Notices · 1971
AEPL is a programming system designed as a tool for the implementation of problem-oriented languages. It is based on a small number of simple but powerful concepts described briefly below. The AEPL system is not yet implemented at the present time; it has been used, however, to define - on paper - a language for the manipulation of graphs. The extensibility of the system stems from the ability to create new data types and from the ability to modify some of the language structures dynamically (syntax and associated semantic as well as some control structures).