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Sir Tony Hoare

By Adrian Kosmaczewski,
861 words, reading time ~5 minutes

It would be unwise and useless to try to summarize in a thousand words the immense contributions of Sir Charles Antony Richard Hoare, also known as Tony Hoare (I suppose we are all good friends in this industry) or, with a more Tolkien feeling, as C. A. R. Hoare. I will settle for “Sir Tony Hoare” in this article; familiar yet respectful enough.

I will try to focus here on the concurrency part, and its obvious contribution to the Go programming language. Suffice to say that when you have Quicksort, communicating sequential processes, a billion-dollar mistake, the Hoare Triple, the Hoare program correctness logic, the dining philosophers problem, a knighthood, and a Turing Award in your résumé, you hardly need an introduction, least of all by me.

(To add more gravitas to our feeling of underachievement, let us remember that Sir Tony Hoare spoke Russian, studied with Andrey Kolmogorov in the Soviet Union, helped implement ALGOL, taught computer science at Oxford, worked as researcher for Microsoft, and was named a Fellow of the Royal Society (actually, maybe I should add the “FRS” suffix to the name, too.) Did I mention that he is also thoroughly considered a kind human being?)

Two years before receiving the Turing Award, Sir Tony Hoare published a seminal paper called “Communicating Sequential Processes” commonly referred to as “CSP”. The fact that there is a Wikipedia page dedicated to the concept should give you some context about the “ground-breakingness” of this paper.

In short, and as Hoare himself explains in an interview, the experience of a failed multiprocessing project took him to elaborate on the complete and absolute banishment of shared state as a conditio sine qua non for process communication; instead, he argued, processes should be independent, isolated, but able to communicate with one another in a formal way.

Yes, pretty much what the Go syntax proposes today. It even borrowed the arrow (prominently used all along Sir Hoare’s paper, representing the various exchanges among parties) as a syntactic element, even though the version we got in the language points to the left, instead of pointing to the right (which in my mind still looks odd, but maybe that is because I am a lefty.)

The question that appears in my mind as I read the paper is, why did Go only appear in 2009? Well, Erlang implemented some of these ideas as back as 1986, so clearly somebody at Ericsson was busy reading important computer science papers. Actually, another programming language you might have not heard about, occam, implemented these ideas even earlier, in 1983.

The ideas behind CSP were expanded in the 1985 book of the same name, a book that is freely available to download today.

If you are interested in learning more about Sir Tony Hoare, check the 2021 book “Theories of Programming: The Life and Works of Tony Hoare” by Cliff B. Jones and Jayadev Misra, and published by the Association for Computing Machinery. Sir Hoare’s book “Structured Programming” co-authored with Ole Dahl and Edsger Dijkstra is freely available on the Internet Archive.

You can also read the July 2024 edition of the Newsletter of the Formal Aspects of Computing Science (FACS) Specialist Group, which was dedicated to Sir Tony Hoare in his 90th birthday, featuring articles from various experts who worked with him.

Alternatively, you can also peruse the various papers shown in the cover image of this article:

Reading About Go

Satisfying the curiosity of those who came to this page looking for books about Go, here go some recommendations.

Cover photo by the author.

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