alt Hacker Newsah i see, thanks. i have no idea what rust code looks like but from the article it sounds like a language where you have a lot of metadata about the intended usage of a variable so the compiler can safety check. thats its trick.
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Thread safety metadata in Rust is surprisingly condensed! POSIX has more fine-grained MT-unsafe concepts than Rust.
Rust data types can be "Send" (can be moved to another thread) and "Sync" (multiple threads can access them at the same time). Everything else is derived from these properties (structs are Send if their fields are Send. Wrapping non-Sync data in a Mutex makes it Sync, thread::spawn() requires Send args, etc.)
Rust doesn't even reason about thread-safety of functions themselves, only the data they access, and that is sufficient if globals are required to be "Sync".
That's a fairly accurate idea of it. Some folks complain about Rust's syntax looking too complex, but I've found that the most significant differences between Rust and C/C++ syntax are all related to that metadata (variable types, return types, lifetimes) and that it's not only useful for the compiler, but helps me to understand what sort of data libraries and functions expect and return without having to read through the entire library or function to figure that out myself. Which obviously makes code reuse easier and faster. And similarly allows me to reason much more easily about my own code.