That’s because the parallelization in the STL is encapsulated. In Haskell and Rust it’s explicit, it’s not just about adding a parameter to an existing function, it’s a general mechanism.
Re:Why I Prefer Functional Programming
by platinumrad on Saturday October 31, 2020 @06:40PM
(#24955777)
Rayon literally works on iterators just like the C++ algorithm library.
Also, succinct expression of parallel algorithms isn't a particularly unique feature. Like half of the named algorithms in the C++ standard library can be parallelized by adding a single parameter.