Comment by SkyMarshal

> FP has more to say about purity of functions, the utility of composition of small parts, the flexibility of composition with small parts, ways to wrap parts of the program that can't be handled that way, and providing an existence proof that despite what an imperative programmer might think it is in fact possible to program this way at a system architecture level.

Adding to that, in my case it also made realize that deterministic elimination of entire classes of errors in large, complex code bases, in a systematic rather than ad-hoc way, is actually possible. Prior to discovering fp, and particularly Haskell's type system, I spent much effort trying to do that with a combination of TDD and increasingly elaborate try/catch/throw error handling. Discovering Haskell's compiler, type system, and monadic quarantining of effects obsoleted all that effort and was a huge eye opener for me. And a nice side-effect is easy, reliable refactor-ability. Being able to apply those concepts to imperative and other programming paradigms is where the real value in fp is, imho. Programmers still wrangling with the Tarpit [1] need to take a look if they haven't already.

[1]:https://news.ycombinator.com/item?id=34954126