(ns myns
  (:require
   [darkleaf.di.core :as di]))

(defn ^{::di/kind :component} sys [{}]
  (println ">>> hello, world"))

@(di/start :sys {:sys (di/ref `sys)
                 `foo (di/ref `bar)})
;; >>> hello, world
; => ExceptionInfo: Missing dependency myns/sys
;    {:type  :darkleaf.di.core/missing-dependency
;     :stack (myns/sys :sys :darkleaf.di.core/implicit-root)}