Hobbit violence

hobbit-violence.clj

; Hobbit violence
; My version of this exercise,
; found at http://www.braveclojure.com/do-things/

(def a-body [
  {:part "head", :size 3}
  {:part "eye", :size 1, :symmetrical true}
  {:part "ear", :size 1, :symmetrical true}
  {:part "mouth", :size 1}
  {:part "neck", :size 2}])

(defn symmetrize-part [body-part]
  (if-not (:symmetrical body-part)
    [body-part]
    [(merge {:side "left"}  body-part)
     (merge {:side "right"} body-part)]))

(defn symmetrize-body [body]
  (mapcat symmetrize-part body))

(defn hit-a-body-part [a-body]
  (let [
    sizes (map :size a-body)
    total-body-size (reduce + sizes)
    target (rand-int (+ 1 total-body-size))
    accum-size (reductions + sizes)
    ; Touched where accum-size >= target
    touched-part (nth a-body
      (first (positions #(<= target %) accum-size)))]
  touched-part))

(defn say-body-part [a-part]
  (println (str
    (when (:side a-part) (str (:side a-part) " "))
    (:part a-part))))

(say-body-part (hit-a-body-part (symmetrize-body a-body)))

positions is part of clojure-contrib, yes?