On Borrow Checking

[jmh530]

On Sunday, 11 May 2025 at 20:43:52 UTC, Paul Backus wrote:
> [snip]
>
> The reason for the negativity is that people do not want "a 
> borrow checker." What they want is more powerful safety 
> analysis. A borrow checker is merely one possible means of 
> achieving that goal.
>
> In business terms, this is a failure of "product-market fit." 
> You are supplying something that there is no demand for. Even 
> if it works perfectly, nobody is going to buy it.

Agreed.

But I think "what people want" and "what's the goal here" are two 
different kinds of questions. What people want is more powerful 
safety analysis. But the reason why Walter started working on 
this was that he saw safety as becoming a bigger issue in 
programming languages, most notably with Rust gaining traction, 
and wanted to help D compete on that basis. So I think one thing 
that has Walter frustrated is that he wants to be able to say D 
has a borrow checker when someone asks, but the actual users 
don't want something unless it actually enables the more powerful 
safety analysis.

And at the same time, people are frustrated with half-baked 
implementations of things. At least if Walter stops working on 
@live, then it wouldn't have been made a part of the language.

But at the end of the day, I think there are a lot of people who 
are on board with more powerful safety analysis, provided it is 
done right.