Alef (programming language)

Concurrent programming language

AlefParadigm| compiled, concurrent, structured

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Designed by| Phil Winterbottom
First appeared| 1992; 32 years ago (1992)
Typing discipline| Static, strong
OS| Plan 9 from Bell Labs
Influenced by
C, Newsqueak
Influenced
Limbo, Rust, Go

Alef is a discontinued concurrent programming language, designed as part of the Plan 9 operating system by Phil Winterbottom of Bell Labs. It implemented the channel-based concurrency model of Newsqueak in a compiled, C-like language.

## History

[edit]

Alef appeared in the first and second editions of Plan 9, but was abandoned during development of the third edition.[1][2] Rob Pike later explained Alef's demise by pointing to its lack of automatic memory management, despite Pike's and other people's urging Winterbottom to add garbage collection to the language;[3] 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."[4]

Alef was superseded by two programming environments.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 operating system. The Alef concurrency model was replicated in the third edition of Plan 9 in the form of the libthread library, which makes some of Alef's functionality available to C programs and allowed existing Alef programs (such as Acme) to be translated.[5]

## Example

[edit]

This example was taken from the Alef reference manual.[1] The piece illustrates the use of tuple data type.

(int, byte*, byte)
func()

return (10, "hello", 'c');

void
main()

int a;
byte* str;
byte c;
(a, str, c) = func();

## See also

[edit]

* Communicating sequential processes
* Plan 9 from Bell Labs
* Go (programming language)

## References

[edit]

1. ^ a b Winterbottom, Phil (1995). "Alef Language Reference Manual". Plan 9 Programmer's Manual: Volume Two. Murray Hill: AT&T.
2. ^ "Preface to the Third (2000) Edition". Plan 9 Manual. Murray Hill: Bell Labs. June 2000. Archived from the original on 2015-02-05. Retrieved 2012-10-29.
3. ^ Pike, Rob (2010). Origins of Go concurrency style. OSCON Emerging Languages Camp. Archived from the original on 2021-12-13.
4. ^ Pike, Rob. "Rio: Design of a Concurrent Window System" (PDF). Retrieved 8 March 2013.
5. ^ "thread(2)". Plan 9 Manual. Retrieved 2012-10-29.

* Flandrena, Bob (1995). "Alef Users' Guide". Plan 9 Programmer's Manual: Volume Two. Murray Hill: Bell Labs.
* Phil Winterbottom (1992-10-20). "Plan9 VM". Newsgroup: comp.os.research. Usenet: 1c1denINN441@darkstar.UCSC.EDU.

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