Limbo (programming language)

Limbo

Paradigm	Concurrent
Appeared in	1995
Designed by	Sean Dorward, Phil Winterbottom, Rob Pike
Developer	Bell Labs / Vita Nuova Holdings
Typing discipline	Strong
Major implementations	Dis virtual machine
Influenced by	C, Pascal, CSP, Alef, Newsqueak
Influenced	Stackless Python, Go
OS	Inferno
License	Open source
Website	http://www.vitanuova.com/inferno/limbo.html

Limbo is a programming language for writing distributed systems and is the language used to write applications for the Inferno operating system. It was designed at Bell Labs by Sean Dorward, Phil Winterbottom, and Rob Pike.

The Limbo compiler generates architecture-independent object code which is then interpreted by the Dis virtual machine or compiled just before runtime to improve performance. Therefore all Limbo applications are completely portable across all Inferno platforms.

Limbo's approach to concurrency was inspired by Hoare's Communicating Sequential Processes (CSP).

Language features

Limbo supports the following features:

• modular programming
• concurrent programming
• strong type checking at compile- and run-time
• interprocess communication over typed channels
• automatic garbage collection
• simple abstract data types.

Examples

Limbo uses Ada style definitions as in:

name := type value;
name0,name1 : type = value;
name2,name3 : type;
name2 = value;

Hello world

implement Command;

include "sys.m";
    sys: Sys;

include "draw.m";

include "sh.m";

init(nil: ref Draw->Context, nil: list of string)
{
    sys = load Sys Sys->PATH;
    sys->print("Hello World!\n");
}

Books

The 3rd edition of the Inferno operating system and Limbo programming language are described in the textbook Inferno Programming with Limbo ISBN 0470843527 (Chichester: John Wiley & Sons, 2003), by Phillip Stanley-Marbell. Another textbook "The Inferno Programming Book: An Introduction to Programming for the Inferno Distributed System", by Martin Atkins, Charles Forsyth, Rob Pike and Howard Trickey, was started, but never released.

See also

• The Inferno operating system.
• Alef - The predecessor of Limbo.
• Plan 9 from Bell Labs
• Go (programming language) - Similar language from Google

External links

• Vita Nuova page on Limbo
• A Descent into Limbo by Brian Kernighan
• The Limbo Programming Language by Dennis M. Ritchie and Addendum by Vita Nuova.
• Inferno Programming with Limbo by Phillip Stanley-Marbell
• Threaded programming in the Bell Labs CSP style
• Limbo on Google Directory