Welcome to the Dictionary of Programming Languages, a compendium of computer coding methods assembled to provide information and aid your appreciation for computer science history.

Browse the dictionary by clicking on a section:
       A  B  C  D  E  F  G  H  I  JK  L  M  N  O  P  QR  S  T  UV  WXYZ+ 

Get a full dump of the dictionary:
       List of Names      Short Form      Full Form

SIMULA

Language type:

O - Object-oriented

Description:

Simula67 is a block-structured procedural language with some object-oriented programming features. It was the first language to supply abstract data type and class support, and is therefore recognized as one of the founding elements of object-oriented computing. Simula syntax is similar to that of Algol, but with special features and keywords for record classes and type support. Other features of Simula include: basic numeric data types, strings, strong type checking, basic control structures, data encapsulation, simple inheritance, simple I/O support, some polymorphism, and special semantics for discrete-event simulation. The execution of a Simula program consists of one or more processes, each of which is an instance of some class. Objects can interact with eachother somewhat independently; Simula supported a primitive form of concurrency (co-routines).
Simula I was designed in 1962 and first implemented in 1964; it was an extension of Algol 60 for discrete-event simulation. In 1967, the more general-purpose Simula67 was introduced, with a wider set of data types and object support. Simula was standardized in 1977. Today, the language is controlled by a small independent standarization body, the SSG, dedicated to ensuring compliance by all Simula language compilers with the official language definition.
Simula is available free for just about every general-purpose computing platform. Some of the Simula implementations are native compilers, and some are Simula-to-C translators. Many free add-on libraries and packages exist, and are available free for Simula programmers. Information about Simula, including programming tutorials and source examples, is surprisingly widely available on the WWW.

Origin:

Ole Dahl and Kristen Nygaard, NCC Olso, 1964-67.

See Also:

Algol    Smalltalk    Ada    C     Eiffel   

Remarks:

Simula was invented in Norway, and has always enjoyed the largest following in Scandinavia. It was never really widely adopted for general-purpose programming, but was and still is used in educational settings.
The Simula language has the distinction of having been stable and useful with almost no changes for 30 years (as compared to Fortran or Lisp, for example!)
Simula may not have been widely adopted, but its influence can be seen in almost every object-oriented language invented since, especially block-structured ones like Eiffel, C , and even Java.

Links:

U. of Montreal SIMULA home page

Association of SIMULA Users

SIMULA download area

Simula Unix CIM FTP Site

Date:

Last updated 12/10/97

Sample code:

Simula Line class, taken from Kathleen Fisher's "Introduction to Simula"

        Class Line(a,b,c); real a,b,c;
        begin
          boolean procedure parallelto(l); ref(Line) l;
            if l =/= none then
                parallelto := abs(a*l.b - b* l.a) < 0.00001;

          ref(Point) procedure meets(l); ref(Line) l;
            begin real t;
                if l =/= none and ~parallelto(l) then
                   begin
                     t := 1/(l.a * b - l.b * a);
                     *** complicated expressions omitted below ***
                     meets :- new Point(..., ...);
                   end;
            end; ***meets***

          real d;

          d := sqrt(a**2   b**2);

          if d = 0.0 then error else
             begin
                d := 1/d;
                a := a * d; b := b * d; c := c * d;
              end;

        end *** Line***

Descriptions in this dictionary are ©1997-99 Neal Ziring. Some examples copyright of their respective authors. Some technologies and languages are trademarked. Permission to copy descriptions is granted as long as authorship credit is preserved.

Comments on this dictionary, corrections and suggestions, are all welcome. Please use email, the address is ziring@home.com