EL1

Extensible Language One. An extensible language by

B. Wegbreit of Harvard ca 1974. EL1 is internally somewhat

Lisp-like, but fully typed with records and pointers. The

external syntax is ALGOL-like and extensible, supporting

user-defined data structures, control structures and

operations. The parser is table-driven, with a modifiable

set of productions. Used as the basis for the ECL

operating system.

["Studies in Extensible Programming Languages", B. Wegbreit,

Garland. Pub 1980].