Sql like join in clojure

gistfile1.clj

(ns workflows-conductor.le-workspace-join
  (:require [clojure.set :refer [difference
                                 intersection
                                 union]]))

(defn inner-join
  [left-keys right-keys]
  (intersection (set left-keys) (set right-keys)))

(defn outer-join
  [left-keys right-keys]
  (union (difference (set left-keys) (set right-keys)) (difference (set right-keys) (set left-keys))))

(defn full-join
  [left-keys right-keys]
  (union (set left-keys) (set right-keys)))

(defn left-join
  [left-keys right-keys]
  left-keys)

(defn map-combine [group1 group2 dumy-map]
  (for [map1 group1
        map2 group2]
    (merge-with #(or %2 %1) dumy-map map2 map1)))

(defn joiner [left-coll right-coll left-fn right-fn join-type]
  (let [left-idx (group-by left-fn left-coll)
        right-idx (group-by right-fn right-coll)
        join-keys (set (join-type (keys left-idx) (keys right-idx)))]
    (mapcat #(map-combine (get left-idx  % [{}])
                          (get right-idx % [{}])
                          (zipmap (set (union (keys (first left-coll)) (keys (first right-coll))))
                                  (repeat nil)))
            join-keys)))


(def one
  [{:foo "bar" :key1 "test1"}
   {:foo "test" :key1 "test2"}])

(def two
  [{:bar "foo" :foo1 "bar"}
   {:bar "bar1" :foo1 "foo1"}])


#_(joiner one two :foo :foo1 left-join)