Insert many entities into Datomic at once

put-many.clj

(require '[datomic.api :as d])

(let [uri  "datomic:dev://localhost:4334/example"
      coll (map (fn [k v] {k v})
                (map (comp keyword str char) (range 97 123))
                (iterate inc 0))
      conn (d/connect uri)]
  (->> (map (fn [m] (assoc m :db/id (d/tempid :db.part/user))) coll)
       (d/transact conn)))

;; {:db/id #db/id [:db.part/user] ...}
;; will fail because the tempid will be the same accross the collection.

;; Mapping (d/tempid :db/part/user) across the data will assign
;; a unique tempid to each map in the collection.
(->> (map (fn [k v] {k v})
          (map (comp keyword str char) (range 97 123))
          (iterate inc 0))
     (map (fn [m] (assoc m :db/id (d/tempid :db.part/user))))
     (map :db/id)
     (distinct?)
     (assert))