Project Elvis

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On Monday, 6 November 2017 at 19:55:13 UTC, Jacob Carlborg wrote:
> On 2017-11-06 20:40, Dmitry Olshansky wrote:
>
>> I’d argue this NOT what we want. Nullability is best captured 
>> in the typesystem even if in the form of Nullable!T.
>
> Yeah, it would be better if the elvis operator good integrate 
> with a nullable/option type as well in addition to null.

What's the point when we can already do it easily in a library, 
and arguably with better ergonomics? 
(http://forum.dlang.org/post/fshlmahxfaeqtwjbjouz@forum.dlang.org)

auto tree = new Node(1,
	               new Node(2),
	               new Node(3,
	                   null,
	                   new Node(4)
	               )
	           );

import std.stdio;
writeln(safeDeref(tree).right.right.val.orElse(-1));
writeln(safeDeref(tree).left.right.left.right.orElse(null));
writeln(safeDeref(tree).left.right.left.right.val.orElse(-1));

vs.

writeln(tree?. right?.right?.val ?: -1);
writeln(tree?.left?.right?.left?.right);
writeln(tree?.left?.right?.left?.right?.val ?: -1);

The functionality is probably a good idea, but a library solution 
is doable today without any acrobatics.