Make templates more dynamic about pdf-stamper

[mdiin]

This is actually quite easily solvable outside in client-code. When building templates like this, they are usually merged together. Using merge-with instead gives the possibility of specifying a more advanced merge function that can handle this case. An example from real-world code:

(defn- template-merge
  [& maps]
  (let [res (apply
              merge-with
              (fn [left-val right-val]
                (cond
                  (and (list? left-val)
                       (list? right-val))
                  right-val

                  (list? left-val)
                  (eval (concat left-val [right-val]))

                  (list? right-val)
                  (eval (concat right-val [left-val]))

                  :default
                  right-val))
              maps)]
    res))

(merge-with template-merge m1 m2) allows m1 and m2 to contain values that are lists such as (+ 70). When merging it will insert the other maps value as the last argument to the function call and evaluate it.