Motive behind !empty() with front() instead of Optional front()

[vitoroak]

On Wednesday, 24 March 2021 at 19:23:21 UTC, Per Nordlöw wrote:
> What's the motive behinds D's range design choice of needing
>
>     if (!empty)
>     {
>         // use front or back
>     }
>
> instead of having front returning an optional/maybe type with 
> enforced pattern matching?
>
> Lack of builtin Optional type?
>
> Choosing the Optional path would have avoided the need for 
> putting error diagnostics such as
>
> https://github.com/dlang/phobos/commit/9bd2f2ba8ff1124a044560c4e6912a13cb5ac694
>
> in the standard library of such an alternative solution.

I think one reason is that unlike Rust, D doesn't have a safe way 
to return Optional!(ref T) so we need front and empty so Ranges 
can return the items by reference.