kotlinx.collections.immutable

ted out from underneath you by a separate thread is a possibility of basically every language with shared memory. Only Rust tries to solve race conditions in the type system and its solution introduces many other problems. He also complains that integer width/signedness casts only offer help from both the type system and the runtime! That's pretty good compared to other languages. Then he complains unsigned types are about the underlying bits not the semantic meaning of the number - well, yes, this is unintuitive but exactly the same as every other language because of the weirdness that inherently emerges when mixing signed with unsigned types. Java refuses to add unsigned numbers at all and they have their reasons for that! Unsigned numbers are really only meant for working with binary data formats, not encoding that something can't be negative. Use a jakarta.validation with a framework like Micronaut or Hibernate Validator if you want that. Likewise for date and times sucking. If you use the long since deprecated classes designed in 1995 then maybe those suck by modern standards, although they're great for beginners. So don't use them: java.time is a modern package that treats timezones rigorously, at the cost of being a bit harder to understand.

cebook.github.io/immutable-js/), or Kotlin's immutable collections (https://github.com/Kotlin/kotlinx.collections.immutable) to enforce a mechanism for mutability.