I can share similar experience. When I started to use Java, I happily digged into collections and stuff. It was quite easy to read and follow. Now with Java 8 I tried to read and follow their streams implementation. That was very hard. They implemented streams for semi-automatic parallelization which I never used and won't ever use and that made otherwise simple concepts just unreadable and unbearable. May be Rust developers tried to cover too big spectrum of the problems at once.