[vbezhenar]

That's why I decided not to invest in Scala. Its standard collections library was so hard to grok that I just decided to stay on Java. I must understand everything in the entire stack I'm using. If I have blind spots, it makes me nervous.

Java is pretty good in that regard, for example. I regularly browse its standard library and it's quite comprehensible. Concurrent stuff is not easy, but I guess that's the nature of underlying algorithms.

Also that's the reason that I don't like Java streams. They're as hairy as Scala collections. I'm avoiding Java streams.

IMO implementation details of any library matters as much as its public API. If library implementation is not nice to read, it's a very bad smell.