"async has a relatively high complexity cost for us due to the 'static bound (cc), cancellation-safety, and restrictions relating to traits and dyn. These currently seem insoluble. Bifurcation between sync and async primitives and ecosystem idiosyncrasies further increase the async tax. Effects-inspired solutions seem unpromising."
"Pre-1.0 Rust had a solution: libgreen. It achieved concurrency in user-space without this bifurcation, but at significant performance, portability and maintenance cost and so was removed. With increased engineering bandwidth this may be worth revisiting. Again the language simplicity would be worth it. (One day I’ll create a PoC of zero-cost wrapping of std::{fs, net} plus fiber::{spawn, select} using generator!)"