gistfile1.clj

(defmacro sandwich [col args & code]
  "[col [prev current next] first-form 1-n-forms last-form]"
  (let [top# (first code)
        meat# (butlast (rest code))
        bottom# (last code)]
  `(remove nil? (apply concat (map-indexed 
     (fn [i# v#]
       (let [~args [(get ~col (dec i#)) v# (get ~col (inc i#))]]
         (cond (= i# 0) [~top# ~@meat#]
               (= i# (dec (count ~col))) [~@meat# ~bottom#]
               :else [~@meat#])))
     ~col)))))




 (sandwich ['bread 'tomato 'lettuce 'bacon 'bread] 
   [before item after]
   'olive
   (when-not after 'mayo)
   (if (= 'tomato before) 
       ['soggy item]
       item)
   (when-not before 'mayo)
   'paper-plate)

;(olive bread mayo tomato [soggy lettuce] bacon mayo bread paper-plate)