classroom distribution

gistfile1.clj

;; I want `classrooms` (the accumulator) to end up looking like this:
;; {"A" #{"a" "d" "g" "j"}
;;  "B" #{"b" "e" "h"}
;;  "C" #{"c" "f" "i"}}
(defn distribute-students
  [students teachers]
  (let [classrooms (into {} (for [t teachers] [t #{}]))]
    (loop [student-pool          students          ;; We'll pare this down as we go.
           classrooms            classrooms        ;; We'll build this up as we go.
           [curr-teacher & more] (cycle teachers)] ;;
      (if (seq student-pool)
        ;; There are still students that need to be assigned to a class.
        (recur (rest student-pool)
               (update-in classrooms [curr-teacher] conj (first student-pool))
               more)
        ;; otherwise, all students have been assigned to a classroom.
        classrooms))))

(println (distribute-students
          ["a" "b" "c" "d" "e" "f" "g" "h" "i" "j"]
          ["A" "B" "C"]))

;; output:
; {A #{a d g j}, B #{b e h}, C #{c f i}}