Abstract This paper describes the development of the programming language Erlang during the period 1985-1997. Erlang is a concurrent programming language designed for programming large-scale distributed soft real-time control applications. The design of Erlang was heavily influenced by ideas from the logic and functional programming communities. Other sources of inspiration came from languages such as Chill and Ada which are used in industry for programming control systems. 1 Introduction This paper describes the development of the Erlang programming language. Erlang is a language which draws heavily from various traditions in the logic, functional and realtime control programming communities. Our goal was to make a language which could be used for building large soft real-time control systems. By large I mean systems with possibly millions of lines of code. By a soft real-time system I mean a system which does not fail catastrophically if a real-time deadline is missed.

doi:10.1016/j.tcs.2008.09.019 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Manuscript

Concurrent programming is indispensable. On the one hand, distributed and mobile environments naturally involve concurrency. On the other hand, there is a general trend towards multi-core processors that are capable of running multiple threads in parallel.

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Abstract. This chapter describes Hume: a functionally-based language for programming with bounded resource usage, including time and space properties. The purpose of the Hume language design is to explore the expressibility/costability spectrum in resource-constrained systems, such as real-time embedded or control systems. It is unusual in being based on a combination of λ-calculus and finite state machine notions, rather than the more usual propositional logic, or flat finite-state-machine models. The use of a strict, purely functional programming notation allows the construction of a strong cost model for expressions, which can then be embedded into a simple cost model for processes. In this chapter, we introduce Hume, describe the Hume Abstract Machine implementation, and show how a high-level cost model can be constructed that relates costs from the abstract machine to Hume source programs. We illustrate our approach with an example adapted from the literature: a simple vending machine controller. 1

I declare that this thesis is my own account of my research and contains as its main content work which has not previously been submitted for a degree at any tertiary education institution. Joel Kelso ii The purported advantages of Visual Programming, as applied to general purpose programming languages, have remained largely unfulfilled. The essence of this thesis is that functional programming languages have at least one natural visual representation, and that a useful programming environment can be based upon this representation. This thesis describes the implementation of a Visual Functional Programming Environment (VFPE). The programming environment has several significant features. • The environment includes a program editor that is inherently

Abstract Some Lisp programs such as Emacs, but also the Linux kernel(when fully modularised) are mostly dynamic; i.e., apart from

Abstract. A unidirectional heap is a heap where all pointers go in one direction, e.g. from newer to older objects. For a strict functional language, such as Erlang, the heap may be arranged so that it is unidirectional. We here present a compacting garbage collection algorithm which utilizes the fact that a heap is unidirectional. Only one memory space is used in our algorithm. In fact, no extra memory is used at all, not even any reserved bits within the cells. The algorithm is quite easy to extend to a variant of generational garbage collection. 1

This paper introduces a new language model, Coqa, for deeply embedding concurrent programming into objects. Every program written in Coqa has the desir-able built-in behaviors of quantized atomicity, mutual exclusion, and race freedom. Such a design inverts the default mode of e.g. Java, where such properties have to be manually coded using primitive language constructs such as synchronized, result-ing in programs that are vulnerable to surprising run time errors. A key property of Coqa is the notion of quantized atomicity: all concurrent program executions can be viewed as being divided into quantum regions of atomic execution, greatly reducing the number of interleavings to consider. So rather than building atomicity locally, with small declared zones of atomicity, we build it globally, down from the top. We justify our approach from a theoretical basis by showing that a formal representation, KernelCoqa, has provable quantized atomicity properties. Then we extend Kernel-Coqa with two I/O models in which we conduct an in-depth study on how I/O affects the atomicity property and establish atomicity theorems with respect to I/O. We perform a series of benchmarks in CoqaJava, a Java-based prototype implementation ii incorporating all of the KernelCoqa features, to demonstrate the practicability of the Coqa model. We give concrete CoqaJava examples of various common concurrent programming patterns which showcase the strength and ease of programming of the language.

The telecommunication company Ericsson is using the functional language Erlang [AVWW96, Erl99] for the implementation of the control software of telephone and data switches, such as the AXD 301 ATM switch [BR98]. For these