What are the unused but useful feature you know in D?

[Eljay]

On Monday, 26 June 2017 at 00:38:21 UTC, Mike wrote:
> IMO, part of the problem is that D has the wrong defaults (e.g. 
> `immutable` by default, `@safe` by default, `final` by default, 
> etc...), so users have to opt in to these things when they 
> should really only be opting out of them.  Unfortunately, 
> changing this would be disruptive and will probably never 
> happen without a fork.

If/when D 3.0 happens, as a breaking change, hopefully the 
defaults can be made to be better right defaults.  (D 1.x to D 
2.x had *cough* some breaking changes.)

I also hope that for D 3.0, both Walter and Andrei play with F# 
or OCaml for a while.  There's a lot of Good Things in F# and 
OCaml that perhaps could be considered for D 3.0.