In 1989 when functional programming was still considered a niche topic, Hughes wrote a visionary paper arguing convincingly "why functional programming matters". More than two decades have passed. Has functional programming really mattered? Our answer is a resounding "Yes!". Functional programming is now at the forefront of a new generation of programming technologies, and enjoying increasing popularity and influence. In this paper, we review the impact of functional programming, focusing on

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... it has changed the way we may construct programs, the way we may verify programs, and fundamentally the way we may think about programs.