Komachi calculation problem

komachi.clj

(defn eval-expr [expr]
  (loop [f expr]
    (let [fst (nth f 0)
	  op1 (nth f 1)
	  scd (nth f 2)]
      (if (= (count f) 3) (op1 fst scd)
	  (let [op2 (nth f 3)
		thd (nth f 4)
		rst (drop 5 f)]
	    (if (or (= op2 #'+) (= op2 #'-))
	      (recur (concat (list (op1 fst scd)) (drop 3 f)))
	      (recur (concat (list fst op1 (op2 scd thd)) rst))))))))

(defn make-exprlist []
  (let [f [#'+ #'- #'* #'/]]
    (for [f1 f f2 f f3 f f4 f f5 f f6 f f7 f f8 f]
      (list 1 f1 2 f2 3 f3 4 f4 5 f5 6 f6 7 f7 8 f8 9))))

(defn komachi []
  (for [flist (make-exprlist)
	:when (= 100 (eval-expr flist))]
    flist))

(comment
  ((1 :+ 2 :+ 3 :+ 4 :+ 5 :+ 6 :+ 7 :+ 8 :* 9)
   (1 :+ 2 :+ 3 :- 4 :* 5 :+ 6 :* 7 :+ 8 :* 9)
   (1 :+ 2 :- 3 :* 4 :+ 5 :* 6 :+ 7 :+ 8 :* 9)
   (1 :+ 2 :- 3 :* 4 :- 5 :+ 6 :* 7 :+ 8 :* 9)
   (1 :+ 2 :* 3 :+ 4 :* 5 :- 6 :+ 7 :+ 8 :* 9)
   (1 :+ 2 :* 3 :* 4 :* 5 :/ 6 :+ 7 :+ 8 :* 9)
   (1 :- 2 :+ 3 :* 4 :* 5 :+ 6 :* 7 :+ 8 :- 9)
   (1 :- 2 :+ 3 :* 4 :* 5 :- 6 :+ 7 :* 8 :- 9)
   (1 :- 2 :* 3 :+ 4 :* 5 :+ 6 :+ 7 :+ 8 :* 9)
   (1 :- 2 :* 3 :- 4 :+ 5 :* 6 :+ 7 :+ 8 :* 9)
   (1 :- 2 :* 3 :- 4 :- 5 :+ 6 :* 7 :+ 8 :* 9)
   (1 :* 2 :* 3 :+ 4 :+ 5 :+ 6 :+ 7 :+ 8 :* 9)
   (1 :* 2 :* 3 :- 4 :* 5 :+ 6 :* 7 :+ 8 :* 9)
   (1 :* 2 :* 3 :* 4 :+ 5 :+ 6 :+ 7 :* 8 :+ 9)
   (1 :* 2 :* 3 :* 4 :+ 5 :+ 6 :- 7 :+ 8 :* 9)))