Modula-2+

Modula-2+ is a programming language descended from the Modula-2 language. It was developed at DEC Systems Research Center (SRC) and Acorn Computers Ltd Research Centre in Palo Alto, California. Modula-2+ is Modula-2 with exceptions and threads. The group which developed the language was led by P. Rovner in 1984.^[1]

Modula-2+

Paradigms	imperative, structured, modular, data and procedure hiding, concurrent
Family	Wirth Modula
Designed by	Paul Rovner, Roy Levin, John Wick
Developer	DEC Systems Research Center (SRC) Acorn Research Center
First appeared	1984; 40 years ago (1984)
Typing discipline	Static, strong, safe
Scope	Lexical
OS	Cross-platform
License	Proprietary
Major implementations
DEC SRC Modula-2+, CAMEL (C and Modula Exexcution Library)
Dialects
DEC SRC
Influenced by
Pascal, ALGOL, Modula-2
Influenced
Modula-3

Main differences with Modula-2:

• Concurrency;^[2] different than the concept of coroutine, which was already part of Modula-2
• Exception handling
• Garbage collection^[2]

Implementations

Modula-2+ was used to develop Topaz, an operating system for the SRC DEC Firefly shared memory asymmetric multiprocessing workstation.^[3] Most Topaz applications were written in Modula-2+, which grew along with the development of the system.^[4] Modula-2+ was also used by Acorn in the ARX operating system, and to build an integrated development environment in the Acorn Research Center (ARC).^[5] Modula-2+ strongly influenced other languages such as Modula-3, but as of 2005, it had disappeared.

The original developers of Modula-2+ were both acquired: Acorn by Olivetti and Digital Equipment Corporation by Compaq. Compaq was bought by Hewlett-Packard. Olivetti sold the Olivetti Research Center and Olivetti Software Technology Laboratory (after bought Acorn ARC) to Oracle Corporation and was later absorbed by AT&T.^[6] DEC have made the SRC-reports available to the public.

See also

• Modula

References

1. Rovner, Paul; Levin, Roy; Wick, John (January 11, 1985). SRC-RR-3 On extending Modula-2 for building large, integrated systems. Hewlett-Packard Labs (Report).
2. DeTreville, John (November 22, 1990). Experience with concurrent garbage collectors for Modula-2+ SRC-RR-64. Hewlett-Packard Labs (Report).
3. Thacker, Charles P.; Stewart, Lawrence C.; Satterthwaite, Edwin H. Jr. (December 30, 1987). Firefly: a multiprocessor workstation SRC-RR-23. Hewlett-Packard Labs (Report).
4. McJones, Paul R.; Swart, Garret F. (September 28, 1987). Evolving the Unix system interface to support multithreaded programs SRC-RR-21. Hewlett-Packard Labs (Report).
5. Cardelli, Luca; Donahue, James; Glassman, Lucille; Jordan, Mick; Kalsow, Bill; Nelson, Greg (November 1989). Modula-3 Report (revised), Research Report 52, SRC-RR-052. Hewlett-Packard Labs (Report). DEC Systems Research Center (SRC).
6. Kossow, Al (August 2001). "Not a RISC by Thursday". Newsgroup alt.folklore.computers,comp.sys.acorn.misc.