Scheme is a language I love. Chez Scheme is even fast. I don't use it because the support for parallel programming looks like 1990. In contrast, one can add a handful of lines to a Haskell program and keep 16 cores busy on a Mac Studio. Even Ruby now cleanly supports parallel execution. We're fast reaching the point where any language that doesn't support parallelism, or only via cumbersome locks and so forth, is a toy.