One glaring problem with perl in this day and age (apart from pass by value by default) is a lack of built-in generators. Python has them. Javascript has them. Go has goroutines. Bet Rust has some macros or something.

Yes, I’m aware of some rotting modules on CPAN that half-assedly implement them, but given that they exactly bolt it on, they are full of gotchas, like Try::Tiny, with which it’s quite easy to forget that a return statement in the try block will do exactly the wrong thing.