Collecting traces from algorithms using dynamic Vars, first version.

dynamic_scoping2.clj

(def ^:dynamic *fix-tree-adjunctions*)
(def ^:dynamic *fix-tree-current-name*)

(defn record-adjunct
  "Records an adjunction performed within fix-tree."
  [phrase adjunct]
  (if (thread-bound? #'*fix-tree-adjunctions*)
    (let [record {:phrase phrase
                  :adjunct adjunct}
          record (if (thread-bound? #'*fix-tree-current-name*)
                   (assoc record :name *fix-tree-current-name*)
                   record)]
      (set! *fix-tree-adjunctions* (conj *fix-tree-adjunctions*
                                         record)))))

(def fixed-trees
  "A map from tree filenames to their fixed versions."
  (binding [*fix-tree-adjunctions* []]
    (let [fixed-trees (into {} (for [[name tree] trees]
                                 (binding [*fix-tree-current-name* name]
                                   [name (fix-tree tree)])))]
      ; As a side effect of transforming all our trees, I have also
      ; recorded the adjunctions performed in the process, so I save
      ; them too.
      (def adjunctions *fix-tree-adjunctions*)
      fixed-trees)))