EL1

Extensible Language One

Ben Wegbreit, Harvard, about 1972

An extensible language, internally somewhat like LISP, but fully typed with records and pointers. The external syntax resembles ALGOL and is extensible, supporting user-defined data structures, control structures and operations. The parser is table-driven, with a modifiable set of productions. It was used as the basis for the ECL operating system.

Studies in Extensible Programming Languages, Ben Wegbreit, Garland Pub, 1980.