Comment by blt

Special keywords like `fn` make parsing simpler. Trailing return types are useful in languages that support generic programming, because they make it easier to write a function whose return type depends on the types of its generic inputs. Even C++ has this feature now, using decltype and arrow notation:

    template<typename T, typename U>
    auto add(T t, U u) -> decltype(t + u)
    {
        return t + u;
    }

C++ is notoriously hard to parse. Consider the "most vexing parse", or the fact that refactoring tools for C++ are always flakier than their Java / C# / Go equivalents, or the fact that https://cdecl.org/ exists. New languages in the "expressive, high performance" niche cannot continue to be held back by C++ syntax.