In his 1980 ACM Turing Award lecture, The Emperor’s Old Clothes, Tony Hoare delivers a masterful and deeply personal narrative, blending technical insight with candid reflections on his own successes and failures in programming language design. Through the lens of his early work on ALGOL, Quicksort, and the ill-fated Elliott 503 Mark II software project, Hoare emphasizes timeless principles: the critical importance of simplicity, correctness, and rigorous error-checking in language design and software engineering.
Hoare warns against the seduction of complexity—how committees and institutions often prefer over-engineered systems that obscure errors and frustrate maintainability. His critique of languages like PL/I and Ada (in its early form) is especially resonant today, when software complexity often outpaces our ability to ensure reliability. He calls for a relentless pursuit of simplicity as the bedrock of reliable, maintainable software.
For modern software engineers, this lecture remains profoundly relevant. It underscores the risks of overengineering, the need for tools that support correctness by design, and the enduring value of readable, verifiable code. In a world still grappling with software reliability in critical systems—from AI to infrastructure—Hoare’s lessons are not historical footnotes but urgent guideposts.
“There are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies.”
Tony Hoare (verified)
“The price of reliability is the pursuit of the utmost simplicity.”
— Tony Hoare (verified)“I was eventually persuaded of the need to design programming notations so as to maximize the number of errors which cannot be made, or if made, can be reliably detected at compile time.”
— Tony Hoare (verified)“Above all, I did not allow anything to be done which I did not myself understand. It worked!”
— Tony Hoare (verified)• Title: The Emperor’s Old Clothes
• Author: Tony Hoare
• Type: Article
• Journal: Communications of the ACM, Volume 24, Issue 2
• Publisher: Association for Computing Machinery (ACM)
• Publication time: February 1, 1981
• Publication place: New York, United States
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