[OT] Why mobile web apps are slow

[Adam D. Ruppe]

On Tuesday, 9 July 2013 at 22:40:31 UTC, bearophile wrote:
> - A less allocating Phobos to produce a bit less garbage;

Yes, and options to pass output ranges to more functions too, 
instead of always returning gc allocated things.

> - Perhaps an annotation to disallow heap allocations in a 
> function or a piece of code;

I don't think that will often get used, especially when we're 
already doing @safe pure const static void foo(); as it is.

> - Some good way to allocate variable length arrays on the stack 
> (http://d.puremagic.com/issues/show_bug.cgi?id=9832 ) (so some 
> arrays produce no garbage);

These might be cool. Something we can do today is use static 
arrays as buffers. In my non-gc D experiments, I've made great 
use of a StackArray!(type, max_capacity) with the convenience 
operators overloaded. Combined with a solid "scope" 
implementation, this could be fast, convenient, and safe.

Of course it would need to have a statically known max length big 
enough to store what you want to store without being too 
wasteful. But I don't think that's particularly hard in most 
cases - at least we have RangeError so it dies gracefully instead 
of buffer overflowing like you'd get i C. (It could also 
automatically grow to the gc heap if the programmer is ok with 
that.)

> - The implementation of "scope" maybe helps a bit;

Yes.

> Is that enough? Rust language designers seem to think that's 
> not enough. Opinions are welcome.

I think if we do scope well enough, we'll have something similar 
to Rust that we can flesh out more in the library.