Alef is a discontinued

concurrent programming language Concurrent computing is a form of computing in which several computations are executed '' concurrently''—during overlapping time periods—instead of ''sequentially—''with one completing before the next starts. This is a property of a syst ...

, designed as part of the

Plan 9 Plan 9 or Plan Nine may refer to: Music * Plan 9 (band), a psychedelic rock band from Rhode Island * ''Plan 9'', an album by Big Guitars From Memphis with Rick Lindy * "Plan 9", a song on the 1993 album ''Gorgeous'' by electronica band 808 Stat ...

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

by Phil Winterbottom of

Bell Labs Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mult ...

. It implemented the channel-based

concurrency Concurrent means happening at the same time. Concurrency, concurrent, or concurrence may refer to: Law * Concurrence, in jurisprudence, the need to prove both ''actus reus'' and ''mens rea'' * Concurring opinion (also called a "concurrence"), a ...

model of Newsqueak in a

compiled 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 primarily ...

, C-like language.

History

Alef appeared in the first and second editions of Plan 9, but was abandoned during development of the third edition.

Rob Pike Robert "Rob" Pike (born 1956) is a Canadian programmer and author. He is best known for his work on the Go programming language and at Bell Labs, where he was a member of the Unix team and was involved in the creation of the Plan 9 from Bell Labs ...

later explained Alef's demise by pointing to its lack of

automatic memory management In computer science, garbage collection (GC) is a form of automatic memory management. The ''garbage collector'' attempts to reclaim memory which was allocated by the program, but is no longer referenced; such memory is called ''garbage''. G ...

, despite Pike's and other people's urging Winterbottom to add

garbage collection Waste collection is a part of the process of waste management. It is the transfer of solid waste from the point of use and disposal to the point of treatment or landfill. Waste collection also includes the curbside collection of recyclable ...

to the language; also, in a February 2000 slideshow, Pike noted: "…although Alef was a fruitful language, it proved too difficult to maintain a variant language across multiple architectures, so we took what we learned from it and built the thread library for C." Alef was superseded by two programming environments. The Limbo programming language can be considered a direct successor of Alef and is the most commonly used language in the

Inferno Inferno may refer to: * Hell, an afterlife place of suffering * Conflagration, a large uncontrolled fire Film * ''L'Inferno'', a 1911 Italian film * ''Inferno'' (1953 film), a film noir by Roy Ward Baker * ''Inferno'' (1973 film), a German ...

operating system. The Alef concurrency model was replicated in the third edition of Plan 9 in the form of the ''libthread''

library A library is a collection of materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or digital access (soft copies) materials, and may be a physical location or a vi ...

, which makes some of Alef's functionality available to C programs and allowed existing Alef programs (such as

Acme Acme is Ancient Greek (ακμή; English transliteration: ''akmē'') for "the peak", "zenith" or "prime". It may refer to: Arts and entertainment * ''Acme'' (album), an album by the Jon Spencer Blues Explosion * Acme and Septimius, a fictional ...

) to be translated.

Example

This example was taken from the Alef reference manual. The piece illustrates the use of

tuple In mathematics, a tuple is a finite ordered list (sequence) of elements. An -tuple is a sequence (or ordered list) of elements, where is a non-negative integer. There is only one 0-tuple, referred to as ''the empty tuple''. An -tuple is defi ...

data type. (int, byte*, byte) func() void main()

References

* * C programming language family Concurrent programming languages Plan 9 from Bell Labs {{prog-lang-stub

History

Example

See also

References