Best documentation is probably the RFC: https://github.com/rust-lang/rfcs/blob/master/text/1598-generic_associated_types.md https://github.com/rust-lang/rfcs/bl

Best documentation is probably the RFC: https://github.com/rust-lang/rfcs/blob/master/text/1598-generic_associated_types.md https://github.com/rust-lang/rfcs/blob/master/text/1598-gene... > Allow type constructors to be associated with traits. This is an incremental step toward a more general feature commonly called "higher-kinded types," which is often ranked highly as a requested feature by Rust users.