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

[rikki cattermole]

On 04/11/2017 1:16 PM, Eljay wrote:
> 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.

Like signatures which I'm working on!

https://github.com/rikkimax/DIPs/blob/master/DIPs/DIP1xxx-RC.md