Speculative: Rust for base system components

[Warner Losh]

On Mon, Dec 31, 2018 at 8:02 AM Warner Losh <imp at bsdimp.com> wrote:

>
>
> On Sun, Dec 30, 2018 at 10:41 PM Eric McCorkle <eric at metricspace.net>
> wrote:
>
>> Before I begin, I want to be clear that everything here is in the realm
>> of speculative, long-term discussion.  My goal is to start a
>> conversation, not to propose anything concrete right now.
>>
>
> Today, this is a losing bid. The cost for rust is high (both in terms of
> people and added compile time), it's not well supported on all our
> architectures (and its robustness on the ones it does support has only been
> tested in limited scenarios), and there's 0 software it enables from day
> one. Plus, since it's a fast evolving language, we'll still need the ports
> to support those things that use it today since the likelihood of a version
> mismatch is high (and supporting 1 version would be a big stretch, multiple
> version is right out). So any sane cost / benefit analysis says: way more
> cost than benefit, forget about it. We simply don't have the man-power to
> maintain a high-cost, zero-benefit component in the tree. Lord knows we
> have a lot of non-zero-cost-with-almost-zero-benefit things in the tree
> today that we need to get rid of.
>
> In the future, when there are actual replacement things written, or there
> are new features written, that will shift the cost / benefit equation. And
> the circumstances about what makes up base will also have shifted, if we're
> lucky, and we'll be able to have a conversation. We imported perl and tcl
> on the speculative notion that people would build great things. That never
> really panned out, and they became a high-cost burden to keep modern for
> only minor benefit. And version skew in Perl was terrible by the end. Forth
> and Lua live in the tree because they have benefit (though Forth will be
> departing, most likely by 13, and definitely by 14). They are also small
> and easy to update to new versions.
>
> And we can't say, with certainty, that if a bunch of rust things show up
> we'll use them in base. We'll have to see what they provide to benefit the
> system.
>
> TBH, there's a stronger case for python than rust: there's actual python
> scripts in the tree today that we have to install a port to use. And there
> the benefit, while not zero, is small and the effort is large compared to
> just dragging it in as a port, so it hasn't been done. It's another fast
> evolving language that requires multiple versions as well...
>
> So write something that everybody wants, that must be in base, and that
> requires rust, and then we can have the conversation...
>

Just re-read this. It sounds a little more negative than I wanted to come
off. I'd only wanted to say today the needle is on 'nope' and I hope people
write enough cool stuff to justify moving the needle off 'nope' :) The last
part of that message seems more muted than I wanted.

Warner