Explore three unexpected yet successful features of the D programming language in this insightful conference talk by Andrei Alexandrescu. Delve into the subjective nature of language design, examining features that initially seemed unimportant but have become widely adopted and appreciated. Learn about functional programming concepts, user-defined types, and compile-time evaluation through practical examples such as factorial implementations, generative programming, and embedded DSLs. Discover how these features have impacted D's ecosystem, including code injection with mixin, bitfields in libraries, and compile-time regular expressions. Gain valuable insights into language design decisions and their long-term effects on programming communities and large-scale software development.