For example, you would write

(define-inline (loop-range stop proc) (let loop ([n 0]) (unless (>= n stop) (proc n) (loop (add1 n))))) (let/ec return (define result 0) (loop-range benchmark-range (lambda (n) (when (>= n benchmark-break) (return result)) (set! result (+ n result)))))

In my actual benchmark, loop-range was in a different module than the let/ec. I also saved the result to a variable to avoid optimizing the loop completely away.