Datomic: constructor-like transaction function

gistfile1.clj

; See http://stackoverflow.com/questions/15595540/datomic-insert-blocks

(require '[datomic.api :as d])
(def uri "datomic:mem://test")
(d/create-database uri)
(def conn (d/connect uri))

(d/transact conn [{:db.install/_attribute :db.part/db
                   :db/id #db/id[:db.part/db]
                   :db/ident :car/model
                   :db/valueType :db.type/string
                   :db/cardinality :db.cardinality/one}
                  {:db.install/_attribute :db.part/db
                   :db/id #db/id[:db.part/db]
                   :db/ident :car/numberplate
                   :db/valueType :db.type/string
                   :db/cardinality :db.cardinality/one}
                  {:db.install/_attribute :db.part/db
                   :db/id #db/id[:db.part/db]
                   :db/ident :renter/name
                   :db/valueType :db.type/string
                   :db/cardinality :db.cardinality/one}
                  {:db.install/_attribute :db.part/db
                   :db/id #db/id[:db.part/db]
                   :db/ident :renter/socialsecuritynumber
                   :db/valueType :db.type/string
                   :db/cardinality :db.cardinality/one}
                  {:db.install/_attribute :db.part/db
                   :db/id #db/id[:db.part/db]
                   :db/ident :rentevent/car
                   :db/valueType :db.type/ref
                   :db/cardinality :db.cardinality/one}                    
                   {:db.install/_attribute :db.part/db
                   :db/id #db/id[:db.part/db]
                   :db/ident :rentevent/renter
                   :db/valueType :db.type/ref
                   :db/cardinality :db.cardinality/one}])

(def new-rentevent (d/function '{:lang :clojure
                             :params [db cm cp rn rs]
                             :code [{:db/id #db/id[:db.part/user -1]
                                     :car/model cm
                                     :car/numberplate cp}
                                    {:db/id #db/id[:db.part/user -2],
                                     :renter/name rn
                                     :renter/socialsecuritynumber rs}
                                    {:db/id #db/id[:db.part/user]
                                     :rentevent/car #db/id[:db.part/user -1]
                                     :rentevent/renter #db/id[:db.part/user -2]}]}))

(d/transact conn [{:db/id #db/id[:db.part/user]
                   :db/ident :new-rentevent
                   :db/fn new-rentevent}])

(d/transact conn [[:new-rentevent "Ferrari" "RENT ME!" "John Smith" "123456789"]])
(d/transact conn [[:new-rentevent "Jaguar" "AVAILABLE" "Kate Nash" "567894345"]])
(d/transact conn [[:new-rentevent "Maserati" "PICK ME!" "Justin Williams" "789134353"]])