Chapter 3
This was a rather pleasant read. If I hadn’t known about pattern matching, this could have been full of AHA moments and WOWs.
I feel like, if anyone experienced with at least one programming language reads chapter 3 before chapter 2, they wouldn’t have as deteriorated experience as one would think. With a little tweak and assumption, these chapters can be read in any order.
Recursion was well explained. I like to think tail recursion became my second nature if I need to use them (Thanks to Project Euler and 99 Problems back in the days), but I agree with the sidebar on Tail vs Body recursion. I might add an article on this: Erlang's Tail Recursion is Not a Silver Bullet as a nice supplementary read.
I wish JavaScript wasn’t used as the initial example for reduce though. It’s not a fault of the book, but a fault with my intolerance of that language.
With my distaste for poorly designed language aside (sorry not sorry), let me add that Enum is one of my favourite modules, in any language. What it (along with its cousins Map, MapSet etc - House of Enumerable) provides never fail to impress me whenever I think about solving problems.
The explanations were fantastic, and the shift to Stream felt natural. My only complain there is that I wanted a bit more piped up examples, but I can understand how the focus is on “Higher Order Functions” and pipes, while it sure feels like it, but really involves macros and overusage of it would shift the focus a little.
The section on Stream deserves a re-read, especially in November when Advent of Code approaches.
I wonder if a few utilities of Enumerable should have been explored in this chapter (i.e. reduce_while, group_by etc), I see especially in Clojure books where they often dedicate a nice summary of useful and thought provoking sequence functions.
All in all, a great chapter that is at par with chapter 2 in terms of foundation building, but a much smaller one.
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