The Crossbeam select! macro waits until one of multiple channel operations is ready, allowing a thread to block instead of repeatedly checking channels. section 10.4.4
Waiting for a worker message
A worker sends 42 through an unbounded channel. The receiving thread waits with select! { recv(rx) -> msg => println!("{:?}", msg) }, producing Ok(42). The recv(rx) syntax belongs to the macro and is not legal ordinary Rust syntax. section 10.4.4
The macro fits channel-based concurrency: worker threads send typed messages, while the receiving thread can coordinate responses or task activity. section 10.4.4
