> In C obviously a UID, a PID, a duration, an inode number, a file descriptor, a counter are all just integers. In Rust you could make all those distinct types

> In C obviously a UID, a PID, a duration, an inode number, a file descriptor, a counter are all just integers. In Rust you could make all those distinct types For various kinds of IDs you can do that in C, too: struct UID { int value; }; A C compiler can pass these in registers to functions (https://wintermade.it/blog/posts/value-struct.html https://wintermade.it/blog/posts/value-struct.html). So, performance impact should be zero. It may be not as nice as other languages, but it isn’t bad, either. If you use C++, it can be made a bit nicer, and you could also have such structs that you can calculate with.