Precise GC state

[Ola Fosheim Grostad]

On Sunday, 26 November 2017 at 19:11:08 UTC, Jonathan M Davis 
wrote:
> We can't even have different heaps for immutable and mutable 
> stuff, because it's very common to construct something as 
> mutable and then cast it to immutable (either explicitly or

This is easy to fix, introduce a uniquely owned type (isolated) 
that only can transition to immutable.

So it is more about being willing to tighten up the semantics. 
Same thing with GC, but everything has a cost.

That said Adam has a point with getting more users, it isnt 
obvious that the costs wouldnt be offset by increased interest. 
Anyway, it seems like C# and Swift are pursuing the domain D is 
in by gradually expanding into more performance oriented 
programming mechanisms... We'll see.