[nwah1]

D had a closed source reference compiler for a long time, and didn't have any major backers.

Rust had Mozilla backing early, and was fully open and transparent in terms of community feedback, and wasn't just making a language that had high level features, but was pioneering a new category of language that added tons of safety guarantees at compile time by default using a new paradigm of enforcing borrowing and ownership.

These safety guarantees are not just in regards to memory safety, but also in regards to data races.

D seems to allow memory safety guarantees, but not by default, and I believe it is enforced at runtime not compiletime.

So Rust was at once more accessible and more exciting.

[WalterBright]

D's only runtime memory safety feature is array bounds checking. (The same as Rust, I believe.) The rest is compile time.

D's compile time memory safety focusses on:

1. @safe and @system code

2. disallowing unsafe pointer operations

3. safe alternatives to pointers

4. controlling escaping of pointers

5. controlling the scope of addresses

[SamReidHughes]

Rust has other runtime memory safety checking, like RefCell.

[jordigh]

D's compiler was never "closed source" if by that you mean "source not visible". It had a weird non-open source license for a long time, but the source has always been visible.

The weird license did use to scare me away, but that's very much a thing of the past now and now it has a standard free license.

https://news.ycombinator.com/item?id=14060846

I don't think D's features are any less exciting than Rust's, but Rust has had a lot of RESF backed by Mozilla.

[ryan_lane]

Source code being visible doesn't make it open source. It had a personal-use-only license, which isn't a valid OSSI license (which is what makes something open source).

[jordigh]

That's why I qualified it with "if that's what you mean by closed source". I don't know if all source is either open or closed and anything that isn't OSI-approved is closed. I don't think that's what people usually mean by "closed source".

I also freely granted that dmd's ad-hoc license wasn't open source despite having visible source.

[Paul-ish]

> D had a closed source reference compiler for a long time, and didn't have any major backers.

In addition, wasn't there for a while two separate and incomparable versions of the standard library that fragmented the community?

[alphaglosined]

That was 9 years ago and the second is no longer maintained (for about 2 years at this point).

[tombert]

That's fair, I suspected that people who knew more about this stuff had a reason.

[p0nce]

Compiling slower than C++ is not exciting.

[FraaJad]

just to be clear, p0nce is referring to rust's compile time. D is known to have very fast compile times (unless you are doing very template heavy meta programming..)