Hot swapping, where code can be changed without stopping a system. The sequential subset of the Erlang language supports eager evaluation, single assignment, and dynamic typing. Danish mathematician and engineer Agner Bitcoin group floats Erlang as well as a syllabic abbreviation of “Ericsson Language”.
Erlang was designed with the aim of improving the development of telephony applications. 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. In 1998 Ericsson announced the AXD301 switch, containing over a million lines of Erlang and reported to achieve a high availability of nine “9”s. In 2006, native symmetric multiprocessing support was added to the runtime system and VM. Process creation and destruction is a lightweight operation.
Message passing is the only way for processes to interact. If you know the name of a process you can send it a message. Processes do what they are supposed to do or fail. If Java is ‘write once, run anywhere’, then Erlang is ‘write once, run forever’. In 2014, Ericsson reported Erlang was being used in its support nodes, and in GPRS, 3G and LTE mobile networks worldwide and also by Nortel and T-Mobile.