Erlang is a general-purpose, concurrent, functional high-level programming language, and a garbage-collected runtime system. The term Erlang is used interchangeably with Erlang/OTP, or Open Telecom Platform (OTP), which consists of the Erlang runtime system, several ready-to-use components (OTP) mainly written in Erlang, and a set of design principles for Erlang programs.[4]
The Erlang runtime system is designed for systems with these traits:
The Erlang programming language has data, pattern matching, and functional programming.[6] The sequential subset of the Erlang language supports eager evaluation, single assignment, and dynamic typing.
A normal Erlang application is built out of hundreds of small Erlang processes.
It was originally proprietary software within Ericsson, developed by Joe Armstrong, Robert Virding, and Mike Williams in 1986,[7] but was released as free and open-source software in 1998.[8][9] Erlang/OTP is supported and maintained by the Open Telecom Platform (OTP) product unit at Ericsson.
- Distributed
- Fault-tolerant
- Soft real-time
- Highly available, non-stop applications
- Hot swapping, where code can be changed without stopping a system.[5]
History
The name Erlang, attributed to Bjarne Däcker, has been presumed by those working on the telephony switches (for whom the language was designed) to be a reference to Danish mathematician and engineer Agner Krarup Erlang and a syllabic abbreviation of "Ericsson Language".[7][10][11] Erlang was designed with the aim of improving the development of telephony applications.[12] The initial version of Erlang was implemented in Prolog and was influenced by the programming language PLEX used in earlier Ericsson exchanges. By 1988 Erlang had proven that it was suitable for prototyping telephone exchanges, but the Prolog interpreter was far too slow. One group within Ericsson estimated that it would need to be 40 times faster to be suitable for production use. In 1992, work began on the BEAM virtual machine (VM), which compiles Erlang to C using a mix of natively compiled code and threaded code to strike a balance between performance and disk space.[13]
Functional programming examples
Factorial
A factorial algorithm implemented in Erlang: is a preprocessor macro for the current module). If there is a new version of the counter module in memory, then its codeswitch/1 function will be called. The practice of having a specific entry-point into a new version allows the programmer to transform state to what is needed in the newer version. In the example, the state is kept as an integer.
In practice, systems are built up using design principles from the Open Telecom Platform, which leads to more code upgradable designs. Successful hot code loading is exacting. Code must be written with care to make use of Erlang's facilities.
Distribution
In 1998, Ericsson released Erlang as free and open-source software to ensure its independence from a single vendor and to increase awareness of the language. Erlang, together with libraries and the real-time distributed database Mnesia, forms the OTP collection of libraries. Ericsson and a few other companies support Erlang commercially.
Since the open source release, Erlang has been used by several firms worldwide, including Nortel and Deutsche Telekom.[36] Although Erlang was designed to fill a niche and has remained an obscure language for most of its existence, its popularity is growing due to demand for concurrent services.[37][38] Erlang has found some use in fielding massively multiplayer online role-playing game (MMORPG) servers.[39]
See also
- Elixir – a functional, concurrent, general-purpose programming language that runs on BEAM
- Luerl - Lua on the BEAM, designed and implemented by one of the creators of Erlang.
- Lisp Flavored Erlang (LFE) – a Lisp-based programming language that runs on BEAM
- Mix (build tool)
- Phoenix (web framework)
- Gleam (programming language) – a general-purpose, concurrent, functional high-level programming language that compiles to Erlang
Further reading
- Early history of Erlang by Bjarne Däcker
External links
References
- N. D. C. Conferences. Joe Armstrong - Functional Programming the Long Road to Enlightenment: a Historical and Personal Narrative Vimeo, 4 June 2014^
- Clojure: Lisp meets Java, with a side of Erlang - O'Reilly Radar radar.oreilly.com^
- Influences - The Rust Reference The Rust Reference, retrieved 2023-04-18