prewalk-splice.clj

(ns adhoc.core
  (:require clojure.walk))

(defn prewalk-splice
  [smap form]
  (if-let [seq-reshaper (cond (seq? form) identity
                              (list? form) (partial apply list) ;; necessary?
                              ;; map entries look like vectors
                              (instance? java.util.Map$Entry form) nil
                              (vector? form) vec
                              (set? form) set)]
    ;; we know how to splice into this form
    (seq-reshaper
     (mapcat (fn [sub] (if (contains? smap sub)
                         (smap sub)
                         [(prewalk-splice smap sub)]))
             form))
    ;; otherwise let walk descend into it
    (clojure.walk/walk (partial prewalk-splice smap) identity form)))

(comment
  (prewalk-splice '{a [1 2 3] b [4 5 6]} '((. a ..) {#{:a b :C} [- b +]}))
  #_((. 1 2 3 ..) {#{:C 4 5 6 :a} [- 4 5 6 +]}))