I bought the book about a year ago which was probably the fourth year of my Kotlin awareness and third year of using it daily in my job as an Android app developer. Skimmed it but did not embrace it for deep learning until a few weeks ago. Now I am forcing myself to deep dive into FP using the book and have most of my development work on hold for a while. My company, my choice. 🙂
It might be interesting to the three of you who got this far to hear my FP story. I first heard of FP in the late 80's at a conference at MIT. I was working with Richard Stallman at the time on Emacs (elisp) but mostly using C. My day job was building high performance computers for a minicomputer company (Data General) writing microcode. It was clear to me that FP was not even close to being ready for prime time use by mainstream software developers. Over the subsequent years though, I kept seeing FP inching forward like a huge freight train heading towards the station but never quite pulling in. I always recognized the inherent value of immutable data and higher order functions but not so much pure functions or algebraic data types.
About six or so years ago, as I was starting Android work for Brightcove, when a half dozen or so engineers decided to do a weekly Haskell lunchtime learning session using the O'Reilly book. Six weeks or so into that effort, I suggested we do a Haskell project of some significance. The two, maybe three, FP/Haskell gurus responded that that was not going to happen as FP and Haskell were merely for intellectual study and still not ready for prime time. My part of that effort ended there.
Then a few years ago I saw that Uncle Bob had bought into FP (using Clojure) which convinced me that the FP train had landed. Arrow's popularity in the Kotlin world did not go unnoticed either.
I am now into parts of Chapters 3, 4, and 5 skimming around but doing all the exercises religiously with IntelliJ. Folding was hurting my brain but I now think I understand it. Took days. So I have a long way to go. Reassuring to have found a space to share the journey with kindred spirits.