e present an experimental programming language y a called Erlang which is suitable for programming telephon pplications. We discuss some of the requirements for such e e a language and introduce the language by a series of simpl xamples which show how both sequential and concurrent m activities can be programmed. We discuss the error recovery echanism used in Erlang together with the performance 1 characteristics of the current implementation. . INTRODUCTION Erlang is a programming language designed for prot g totyping concurrent real-time distributed applications. I rew out of a series of experiments [1,2,3] aimed at creating y a a language suitable for programming large scale telephon pplications. Some of the main characteristics of the 1 language are as follows: .1. Robustness In programming large systems many small program- - m ming errors will be made - we view this as inevitable. For al systems and exhaustive test procedures are currently not s capable of ensuring fault f...

This paper describes how Prolog was used for the development of a new concurrent realtime symbolic programming language called Erlang. Erlang was developed by first building a prototype in Prolog - the prototype was used by a user group to test their reactions to the language. As time passed many features were added (and removed) from the interpreter and eventually the language reached a level of maturity where it was decided to try it out on a significant problem. About 3 years and some 20,000 lines of Erlang later, performance became an issue - we wrote Prolog cross compilers from Erlang to various concurrent logic programing languages followed by a direct implementation of Erlang itself. The direct implementation of Erlang was loosely based on the WAM and made by writing a Prolog compiler from Erlang to a new abstract machine and an emulator for the abstract machine in 'C'. The instruction set for the abstract machine was first prototyped in Prolog - finally the compiler was re-writ...