(use-modules (ice-9 popen)
             (ice-9 rdelim)
             (srfi srfi-1))

(define* (authors #:optional (range "HEAD"))
  "Return a list of authors for commit RANGE."
  (let* ((port (open-pipe* OPEN_READ
                           "git" "log" "--format=%aN <%aE>" range))
         (output (read-string port)))
    (close-port port)
    (let ((authors (string-split output #\newline)))
      (delete-duplicates authors))))

;; (authors "v0.8.2..HEAD")