Clojure's core.async channel concurrency is nothing like go's. You need to wrap your concurrent block in a macro so it can code walk to find explicit blocking points. That means these points need to be marked, and can't be in already compiled functions. That's an enormous limitation. Compare to go's which just works, no caveat.
Plus Go is just so nice with the automatic IO handoff. But in a functional language I really don't think it's as big a limitation- still large, but not as bad as it could be. The pattern of writing mostly small, pure functions and then piping them together with channels all at the end is pretty workable.
