Also as with C++ having a more expressive language means that while you could have done it in C in practice you won't because it sucks to do all this extra labour, whereas in Rust it's fine because the machine did all the hard work.
Monomorphization is an example where that happens, in C if we're sorting and de-duplicating Geese, Customers and BugReports, we're either writing three separate functions dedup_geese, dedup_customers and dedup_bug_reports, or we're using function pointers and we incur the function call overhead when our functions get called. Ouch.
In Rust (or C++) the monomorphization step is going to turn sort & dedup for Geese, Customers and BugReports into separate functions†, and yet we only wrote the code once.
To some extent you can try to mimic this in C via the "X macro" strategy, but now you're not even just writing C any more, you're writing the macros and maybe running them through pre-processing and trying to understand if the result does what you meant, it's a pretty horrible way to work, so again you're discouraged from doing it.
†However the compiler may spot that actually the machine code implementation for say, BugReport and Goose is identical and so it only emits one in the eventual binary with the other just aliased - which may confuse a debugger and thus a human trying to debug it.
Monomorphization is an example where that happens, in C if we're sorting and de-duplicating Geese, Customers and BugReports, we're either writing three separate functions dedup_geese, dedup_customers and dedup_bug_reports, or we're using function pointers and we incur the function call overhead when our functions get called. Ouch.
In Rust (or C++) the monomorphization step is going to turn sort & dedup for Geese, Customers and BugReports into separate functions†, and yet we only wrote the code once.
To some extent you can try to mimic this in C via the "X macro" strategy, but now you're not even just writing C any more, you're writing the macros and maybe running them through pre-processing and trying to understand if the result does what you meant, it's a pretty horrible way to work, so again you're discouraged from doing it.
†However the compiler may spot that actually the machine code implementation for say, BugReport and Goose is identical and so it only emits one in the eventual binary with the other just aliased - which may confuse a debugger and thus a human trying to debug it.