资料来源 : Free On-Line Dictionary of Computing

EL1
     
        Extensible Language One.  An extensible language by
        B. Wegbreit of Harvard ca 1974.  EL1 is internally somewhat
        {Lisp}-like, but fully typed with {record}s and pointers.  The
        external {syntax} is {ALGOL}-like and extensible, supporting
        user-defined {data structure}s, 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].