From the D Blog: A Pattern for Head-mutable Structures

[Per Nordlöw]

On Thursday, 25 June 2020 at 11:55:14 UTC, Mike Parker wrote:
> Simen Kjærås outlines an approach to supporting head-mutable 
> types in D without the need for compiler or language changes.
>
> The blog:
> https://dlang.org/blog/2020/06/25/a-pattern-for-head-mutable-structures/
>
> Reddit:
> https://www.reddit.com/r/programming/comments/hfkq5e/a_pattern_for_headmutable_structures_in_d/
>
> I've also submitted it to HN (please use the search box):
>
> https://news.ycombinator.com/newest

What's so problematic about adding compiler support for implicit 
cast to head mutable for range-style structs?