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Language peer sets for EL1:
United States
United States/1970
Designed 1970
1970s languages
Third generation
High Cold War
Genus Grammar and Syntax-oriented
Grammar and Syntax-oriented
Grammar and Syntax-oriented/1970
Grammar and Syntax-oriented/United States
Language-related/United States
Content-reflexive/United States


Extensible Language 

alternate simple view
Country: United States
Designed 1970
Genus: Grammar and Syntax-oriented

Extensible Language One.

B. Wegbreit, Harvard ca 1974.

An extensible language, 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.

One of many experiments to use Algol syntax with S-expressions

from Steele "Evolution of Lisp"
The EL1 language was designed by Ben Wegbreit as part of his Ph.D. research [Wegbreit, 1970]. It may be loosely characterized as a Lisp with an Algol like surface syntax and strong data typing. A complete programming system called ECL was built around EL1 at Harvard in the early 1970 s [Wegbreit, 1971; Wegbreit, 1972; Wegbreit, 1974] The UNION function in EL1 looks like this: union ..."

from Shutt "Recursive Adaptible Grammars"
"Wegbreit s ECFGs In the late 1960s, Ben Wegbreit developed an adaptable grammar formalism, as part of an extensible programming language called EL1. Extensible languages will be mentioned in x3.4. He called his grammars ECFGs (Extensible Context Free Grammars) The basic reference is [Wegb 70] An ECFG G consists of a context free grammar together with a deterministic finite state transducer (see x1.4.2) The input alphabet of the transducer is TG ; the output alphabet is ZG , plus some reserved symbols that are used for the unambiguous expression of rules. The output of the ....

Related languages
ALGOL 60 EL1   Influence
ECL EL1   Written using
LISP 1.5 EL1   Influence
EL1 VERS2   Built on

  • Wegbreit, B. (1970) Wegbreit, B. "Studies in extensible programming languages." Technical Report ESD-TR-70-297. Harvard University, Cambridge, Massachusetts. May 1970.
  • Wegbreit, B., (1974) Wegbreit, B., "The Treatment of Data Types in EL1"
          in [ACM] (1974) [ACM] CACM 17(05) (May 1974)
  • Wegbreit, Ben (1974) Wegbreit, Ben "Procedure closure in EL1" p38-43 Abstract
          in (1974) The Computer Journal 17(1) February 1974
  • Spitzen, J. and Wegbreit, B. (1975) Spitzen, J. and Wegbreit, B. "The verification and synthesis of data structures" ACTA Informatica, 4, 2 (1975), 127-144.
          in (1974) The Computer Journal 17(1) February 1974
  • Leeuwen, J. (1976) Leeuwen, J. Van review of Spitzen 1975 Abstract
          in (1976) ACM Computing Reviews 17(02) March 1976
  • (1976) The Higher Order Language Working Group (HOLWG) Working Paper on 23 exisitng programming languages
          in (1976) ACM Computing Reviews 17(02) March 1976
  • Sammet, Jean E (1978) Sammet, Jean E "Roster of programming languages for 1976-77" pp56-85
          in [SIGPLAN] (1978) SIGPLAN Notices 13(11) Nov 1978
  • Wegbreit, B. (1980) Wegbreit, B. "Studies in Extensible Programming Languages" Garland Pub 1980.
          in [SIGPLAN] (1978) SIGPLAN Notices 13(11) Nov 1978
  • G.L. Steele et al, (1993) G.L. Steele et al, "The Evolution of Lisp"
          in [HOPL II] (1993) [ACM SIGPLAN] SIGPLAN Notices 28(03) March 1993 The second ACM SIGPLAN conference on History of programming languages (HOPL II)
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