I’ll leave this here. It’s a personal project on my behalf, not on the name of the Arrow maintainer’s team. Recording this stuff takes a big effort so I’ve been a couple of months putting time on it here and there. It’s gonna be 1 week for FREE and then paid under subscription following http://caster.io rules. We’ve agreed on leaving around 5 free lessons from that moment on and the rest paid. It’s mostly Android oriented, as a good start to do FP over Kotlin to write Android apps. I honestly think it has enough content to start on FP in the Android world and learn some interesting concepts. It would have been a bit too much to go further and deeper on FP. That also leaves plenty of room for recodring a second one in case people likes it. So I hope the ones interested on this like it 🙂 Big thanks to all the Arrow maintainers who helped on this and also to any contributors making Arrow grow everyday. https://twitter.com/JorgeCastilloPr/status/963771190115487744

Hi, @Jorge Castillo! First of all, congratulations on the course! I got really excited seeing it, and I already started taking a deep dive into it 🙂 However, I am confused regarding your definition of referential transparency from lesson #2. If I understood correctly, there you say that the explicitness of the return type makes the function referentially transparent. But according to every definition I found on the Internet, referential transparency means that a function can be swapped with it’s return value without changing the application’s behaviour. Did I miss something from your explanation?

TO me that would mostly be the definition of a pure function, where you can replace it by it’s return type because you know it will always return the same value for the same inputs, every single time

in my view, pure functions and referential transparent functions are overlapping concepts, or better said, pure functions need to be referentially transparent, and they don’t have any observable side effects

I see it the same was as you Eduard, but this is often explained in various ways...

I’ve only ever read definitions of Referential Transparency as described by Eduard as well.