The thing I found confusing with traits and their generic system was the choice to include "associative types" for out types instead of also defining them in a

The thing I found confusing with traits and their generic system was the choice to include "associative types" for out types instead of also defining them in a generic bound: trait Iterator { type Out; fn next() -> Option<Out>; } vs trait Iterator<T> { fn next() -> Option<T>; } Multiple ways to do something has made it harder to understand.