(defun contexts-list-to-prob-dist (contexts-list)
  "A closure that converts a list of context objects to a probability distribution over words, given said entity pair."
  (let ((local-hash (make-hash-table :test 'equalp))
	 (new-bm-vector (make-array (length *reference-vector*)))
	 (context-count (length contexts-list))
	 (mu 0))
    (flet 
	((magical-word-counter (thiscontext)
	   (print thiscontext)
	   (let ((string-this-context (middle thiscontext)))
	     (unless (equalp string-this-context 0)
	       (map nil #'(lambda (word) (incf (gethash word local-hash 0.0))) (cl-ppcre:split "\\s+" string-this-context)))))
	   
	 (calc-context-probs ()
	   (loop 
	      for feature being the hash-keys of local-hash
	      using (hash-value feature-count)
	      do (setf (aref new-bm-vector (position feature *reference-vector*)) (dirichlet-calc feature feature-count mu context-count)))
	   (loop 
	      for feature being the hash-keys of *corpus-fc-table* ;backoff if we've got no counts locally for a feature. Try commenting this out, see what happens.
	      using (hash-value feature-count)
	      unless (gethash feature local-hash) do (setf (aref new-bm-vector (position feature *reference-vector*)) (dirichlet-calc feature 0 mu context-count)))))
      
      ;(print contexts-list)
      (map nil #'magical-word-counter contexts-list);This counts all occurances of a feature (i) in a context (j), storing the results in local-hash, above.
      (setf mu (count-all-features local-hash))
      (calc-context-probs)
      (make-prob-dist *reference-vector* new-bm-vector))))

(defun normalize-context-matrix (context-matrix)
  "The toplevel normalizer function. Takes a context matrix and destructively replaces each cell with a normalized probability."
  (map-into-matrix context-matrix  #'contexts-list-to-prob-dist)
  (setf *norm-cm* context-matrix))


(defun map-into-matrix (matrix func)
  (let ((flattened-matrix (make-array (array-total-size matrix) :displaced-to matrix)))
    (map-into flattened-matrix (thereis func) flattened-matrix)
    matrix))

(defun thereis (fn)
  #'(lambda (&rest args)
      (when (every (complement #'null) args)
	(apply fn args))))

The value NIL is not of type (MOD 536870911).