Apologies for any mistaken terminology--I'm quite new to computer science, and I pretty much only know Clojure (but I guess I'd say I know it pretty well).

So, I haven't done a ton of research on this, but I've sometimes found it useful when writing Clojure code to be able to refer to some "intermediate version of whatever data structure I'm in" from within that data structure (a lot like in a let). Quick examples:

=> (self-ish {:a 10
              :b (inc (this :a))
              :c (count (vals this))})
=> {:a 10, :b 11, :c 3}
=> (self-ish ["a" "b" (reduce str this)])
=> ["a" "b" "ab"]
//Works in any nested bits too
=> (self-ish [1 2 3 [4 5 (first this)] 6 [7 [8 (cons (second this) (nth this 3))]]])
=> [1 2 3 [4 5 1] 6 [7 [8 (2 4 5 1)]]]

The idea is that the structure builds itself up incrementally, and at any stage has the ability to refer to the current intermediate structure as this. Here's the code for my current implementation:

//Random straightforward but helpful definitions
(defn map-entry? [obj]
  (instance? clojure.lang.AMapEntry obj))
(def Map clojure.lang.IPersistentMap)
(def Vector clojure.lang.IPersistentVector)
(def List clojure.lang.IPersistentList)
(def Set clojure.lang.IPersistentSet)

(defn append
  [x coll]
  (if-not coll x
    (condp instance? coll
      Map (if (empty? x) coll
            (assoc coll (first x) (second x)))
      Vector (conj coll x)
      Set (conj coll x)
      List (apply list (concat coll [x]))
      (concat coll [x]))))

(defn build-this
  [acc-stack acc]
  (->> (cons acc acc-stack)
       (drop-while list?)
       (drop-while (every-pred empty? identity))
       (reduce append)))

(defn self-indulge
  [acc-stack acc form]
  ;//Un-comment the following to see it print intermediate stages of processing
  #_(println "this:" (build-this acc
macros clojure self-reference
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