Haskell also solves data races and use-after-free (with immutability and GC), so it's not surprising the author isn't impressed by Rust's fearless concurrency.

Haskell also solves data races and use-after-free (with immutability and GC), so it's not surprising the author isn't impressed by Rust's fearless concurrency. But debugging deadlocks in threaded code is a piece of cake compared to the hell of data races (attach debugger, and stack traces will show what is deadlocking vs races happening randomly, often impossible to reproduce in a debugger).