There is a bug in a code listing in the article:
val exclaimed = strings.map { it + "!" }
Should be
val exclaimed = plain.map { it + "!" }
val exclaimed = strings.map { it + "!" }
Should be
val exclaimed = plain.map { it + "!" }
I have mentioned this before but the reason I like Java so much is the mature and cohesive ecosystem. Every single problem has been solved in Java and all the solutions look similar so you can readily pick them up. I don’t find that to be the case in other languages.