gistfile1.clj

          (is (= (assoc node2 :id "1")                                                              
                 (-> layer-name                                                                     
                     (write-txn (assoc-node "1" node2)                                              
                                (update-node "1" assoc :baz [1 2 3])                                
                                (update-node "1" dissoc :baz))                                      
                     (get-node "1"))))
          ;; the above is sugar for the below. seem useful?
          (dotxn layer                                                                              
            (-> layer                                                                               
                (assoc-node "1" node2)                                                              
                (update-node "1" assoc :baz [1 2 3])                                                
                (update-node "1" dissoc :baz)))                                                     
          (is (= (assoc node2 :id "1") (get-node layer-name "1")))                                  

;; implementation:
(defmacro write-txn [layer-name & actions]                                                          
  `(let [layer-name# ~layer-name                                                                    
         layer# (layer layer-name#)]                                                                
     (retro/dotxn layer#                                                                            
                  (-> layer#                                                                        
                      ~@actions))                                                                   
     layer-name#))