[wmccullough]

Thank you for the explanation!

If someone such as myself wanted to understand the philosophy of functional languages, do you have any book you'd recommend? Learning the languages is easy enough, but if I ever tried them I'd want to do it using the ideals of functional programming vs. trying to contort the language to be something it isnt't.

I'm noticing a trend more and more where developers move to FP over OOP after a decade or so in their career. I feel if I don't give it a look, I could be missing an obvious lesson.

[lmm]

I would recommend ML for the Working Programmer (available free online on the author's site). Learning ML forced me to write in a properly functional style rather than writing "C in $LANGUAGE" (the book doesn't even mention the possibility of using mutable variables until quite late on); by the same token I'm not sure the language is that usable in the "real world" (I work in Scala these days), but the lessons from it were useful even when I was working in Python.

[AlexanderNull]

While Scala isn't a pure functional language there are some good resources for picking up FP related concepts with it (and it's what I recently moved over to so it's most recent for me). Scala with Cats did a pretty good job for me at describing things in relatable terms. "The Red Book" (Functional Programming in Scala) goes a bit more in depth on these concepts but has a pretty steep learning curve compared to the cats book.

Also check out anything Haskell/Eta/OCaml for server side (and probably also a bit of a steep learning curve) or if you're currently a front end developer CHECK OUT ELM NOWWWWWW. Core beginner concepts to youtube would be currying, higher order functions, and composition. Monads will come once you've mastered map/flatMap/reduce/fold chaining.

[brightball]

There are different extremes. Elixir is one that keeps things developer friendly and enforces everything. The new Programming Elixir book is probably a good place to start. It has constructs that definitely smooth the transition...and it’s really just a wonderful language.

Plus the runtime is excellent for server side.