Breaking D2 language/spec changes with D1 being discontinued in a month

[Jonathan M Davis]

On Wednesday, November 28, 2012 07:44:39 Andrei Alexandrescu wrote:
> On 11/28/12 3:01 AM, Jacob Carlborg wrote:
> > TDPL was release way, way too soon. It was written before many of the
> > features were even implemented. Then at a later stage "Whoops, this
> > apparently doesn't work, we need to break TDPL".
> 
> I disagree. Aside from a few details, the language described by TDPL is
> implementable. The problem becomes when TDPL gets in competition with
> incorrect code that currently compiles and runs although it shouldn't.

That's mostly true, but there are some features which have required further 
ironing out even if TDPL is mostly correct about them still (e.g. pure and 
shared), and some features _still_ aren't properly implemented (e.g. 
synchronized and alias this).

I'm not about to say that TDPL was released too early (it's been a _great_ 
resource and has undoubtedly helped the community grow), but at the same time, 
it doesn't quite represent what the language actually is, and we're slow at 
catching up with it. So, in that sense, if TDPL is meant to be a definitive 
resource, it would have been nice to have the implementation be closer to 
where TDPL is before having released it

However, a _big_ benefit from having not delayed its release was that that a 
lot of stuff stopped changing after that. We stopped making huge, incompatible 
changes from release to release of the compiler. We didn't stop making 
breaking changes, but for the most part, we stopped trying to design the 
language and instead have focused on finishing implementing it. All of the 
design work that has happened since then has either fixed a pressing problem 
caused by the current design (e.g. weak purity) or introduced new, compatible 
features (e.g. SIMD). We're no longer doing stuff like changing how operator 
overloading works just because we came up with a cooler, better way to do it.

- Jonathan M Davis