The c++ notation for functions (and types in general) is horrible, and makes parsing much more expensive than it needs to be. Fixing it is step one if you are making a modern language.

A compatibility required by C.

To avoid any possibility of reintroducing the Most Vexing Parse?

https://en.wikipedia.org/wiki/Most_vexing_parse

It doesn't, but you can pretend it does:

  auto my_function(int, double) -> int;

They probably want to use the same arrow signature and need something in place of auto as omitting it completely would complicate parsing.