Promises in D

[Calvin P]

On Wednesday, 7 April 2021 at 06:51:12 UTC, Vladimir Panteleev 
wrote:
>
> Going even lower, there are callbacks/delegates. In JavaScript, 
> there are few reasons to use callbacks today, because they are 
> much less composable and don't provide much other benefit. 
> However, there is one reason in D where callbacks trump both 
> fibers and promises: a callback's caller controls the lifetime 
> of the passed values, whereas promises require that their held 
> value either is owned by the promise, or has infinite lifetime 
> (i.e. is immutable and on the heap). So, if you were to write a 
> low-level high-performance networking library, you would 
> probably want to have:
>
> [...]

I use refCount to pass resource with promises provide by QuickJS, 
It also work well with async IO code based on D.