Limbo is a

programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

for writing distributed systems and is the language used to write applications for the Inferno operating system. It was designed at

Bell Labs Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the compa ...

by Sean Dorward, Phil Winterbottom, and

Rob Pike Robert Pike (born 1956) is a Canadian programmer and author. He is best known for his work on the Go programming language while working at Google and the Plan 9 operating system while working at Bell Labs, where he was a member of the Unix t ...

. The Limbo

compiler In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primaril ...

generates

architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and construction, constructi ...

-independent

object code In computing, object code or object module is the product of an assembler or compiler In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' ...

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), as implemented and amended in Pike's earlier

Newsqueak Newsqueak is a concurrent programming language for writing application software with interactive graphical user interfaces. Newsqueak's syntax and semantics are influenced by the C (programming language), C language, but its approach to concurr ...

language and Winterbottom's Alef.

Language features

Limbo supports the following features: *

modular programming Modular programming is a software design technique that emphasizes separating the functionality of a program into independent, interchangeable modules, such that each contains everything necessary to execute only one aspect or "concern" of the d ...

* concurrent programming * strong

type checking In computer programming, a type system is a logical system comprising a set of rules that assigns a property called a ''type'' (for example, integer, floating point, string) to every '' term'' (a word, phrase, or other set of symbols). Usu ...

at compile and run-time * interprocess communication over typed channels * automatic garbage collection * simple abstract data types

Virtual machine

The Dis virtual machine that executes Limbo code is a CISC-like VM, with instructions for arithmetic,

control flow In computer science, control flow (or flow of control) is the order in which individual statements, instructions or function calls of an imperative program are executed or evaluated. The emphasis on explicit control flow distinguishes an '' ...

, data motion,

process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management * Business process, activities that produce a specific s ...

creation, synchronizing and communicating between processes, loading modules of code, and support for higher-level data-types: strings, arrays, lists, and communication channels. It uses a hybrid of reference counting and a real-time garbage-collector for cyclic data. Aspects of the design of Dis were inspired by the AT&T Hobbit microprocessor, as used in the original BeBox.

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)

Books

The 3rd edition of the Inferno operating system and Limbo programming language are described in the textbook ''Inferno Programming with Limbo'' (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,

and Howard Trickey, was started, but never released.

References

External links

Vita Nuova page on Limbo

A Descent into Limbo
by

Brian Kernighan Brian Wilson Kernighan (; born January 30, 1942) is a Canadian computer scientist. He worked at Bell Labs and contributed to the development of Unix alongside Unix creators Ken Thompson and Dennis Ritchie. Kernighan's name became widely known ...

The Limbo Programming Language
by Dennis M. Ritchie an
Addendum
by Vita Nuova.
Inferno Programming with Limbo
by Phillip Stanley-Marbell
Threaded programming in the Bell Labs CSP style
* * . * . * . {{DEFAULTSORT:Limbo (Programming Language) Concurrent programming languages Free and open source compilers Inferno (operating system) Programming languages created in 1995 Virtual machines