Yes, but he's talking about an equivalent of Rust's [must_use]. I actually made a post on the Rust subreddit inquiring why Rust made must_use opt-in instead of

Yes, but he's talking about an equivalent of Rust's [must_use]. I actually made a post on the Rust subreddit inquiring why Rust made must_use opt-in instead of opt-out like Swift and, apparently, F#. The reaction was OVERWHELMINGLY negative toward the idea of it being opt-out, which I find very surprising considering the kind of code one typically sees in Rust.