Agree that the types accomplish basically exactly what I want.
If it gets a decent community / ecosystem I think it would be a frontrunner for sure, especially for web apps.
One potential issue is that the runtimes it targets are not that great at processing - they fanout well on BEAM but may not be the best for heavy processing. Not a deal breaker but smth that others like F#, OCaml, Rust can outperform in if the other attributes do well.