Add GC-free closures to D, similar to the ones C++ has

[James Lu]

On Thursday, 5 September 2019 at 14:46:08 UTC, James Lu wrote:
> Add GC-free closures to D. Less GC reliance means less memory 
> fragmentation, enabling lower-level uses of D to use closures.
>
> This has precedent in C blocks and in C++'s lambdas.

The first question should be, does the current closure semantics 
support GC-free deallocation?