>if writing trivial data-structures in Rust is a great challenge, it shows that writing other, less trivial things in Rust will be much more challenging than might be preferred.
Data structures are exactly the abstractions built on top of raw memory. Rust is not really geared toward working with raw memory; it's geared toward working with abstractions that hide the raw memory (i.e., data structures). That's why writing data structures in Rust is hard, and it's also why that fact doesn't imply that "other things" (i.e., code that is not part of a data structure implementation) are hard.
In other words, the fundamental flaw with the assumption that there is a relationship between the difficulty of implementing data structures in Rust and the difficulty of writing applications in Rust is that the two involve very different programming models, and Rust has much more ergonomic support for one than the other.
Data structures are exactly the abstractions built on top of raw memory. Rust is not really geared toward working with raw memory; it's geared toward working with abstractions that hide the raw memory (i.e., data structures). That's why writing data structures in Rust is hard, and it's also why that fact doesn't imply that "other things" (i.e., code that is not part of a data structure implementation) are hard.
In other words, the fundamental flaw with the assumption that there is a relationship between the difficulty of implementing data structures in Rust and the difficulty of writing applications in Rust is that the two involve very different programming models, and Rust has much more ergonomic support for one than the other.