Alef is a discontinued
concurrent programming language
Concurrent computing is a form of computing in which several computations are executed ''Concurrency (computer science), concurrently''—during overlapping time periods—instead of ''sequentially—''with one completing before the next starts ...
, designed as part of the
Plan 9 operating system
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...
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
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 language, but its approach to concurrency was inspired by C. A. ...
in a
compiled
In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs that ...
,
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 La ...
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 m ...
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), ''Inferno'' (1953 film), a film noir by Roy Ward Baker
* Inferno (1973 fi ...
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 vir ...
, 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()
See also
*
Communicating sequential processes
In computer science, communicating sequential processes (CSP) is a formal language for describing patterns of interaction in concurrent systems. It is a member of the family of mathematical theories of concurrency known as process algebras, or pro ...
*
Plan 9 from Bell Labs
Plan 9 from Bell Labs is a distributed operating system which originated from the Computing Science Research Center (CSRC) at Bell Labs in the mid-1980s and built on UNIX concepts first developed there in the late 1960s. Since 2000, Plan 9 has be ...
References
*
*
C programming language family
Concurrent programming languages
Plan 9 from Bell Labs
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