It's interesting to see that they let you mix markup with logic directly in rust, but I have worries about maintainability. I remember the bad old days of PHP where you'd mix markup with logic directly, even when doing OOP with classes and it really made things more difficult long term.
It’s not a rust thing. Custom markup is usually implemented in rust frameworks using macros. If mixing macros and logic becomes a problem, we can change how the macros are implemented.