custom selector support

[OliverM]

Custom selectors like the following work fine in Enlive but aren't supported in Kioo yet:

(defn text= [s] (pred #(= s (text %))))

Attempting to use text= in a kioo selector currently gives a null-pointer error on compilation.

[jaen]

If I remember how kioo works correctly then this is caused by symbols in selector being resolved inside net.cgrand.enlive-html- https://github.com/ckirkendall/kioo/blob/master/src/kioo/core.clj#L74-L75.
If your symbol isn't there it won't get resolved and you'll get a nil which causes the NPE.

A possible fix would be to leave a symbol as-is if resolve-enlive-var can't find it, for example like so:

(defn eval-selector [sel]
  (reduce
    (fn [sel-acc sel-frag]
      (conj sel-acc
          (cond
           (list? sel-frag) (apply (resolve-enlive-var (first sel-frag)) (eval-selector (rest sel-frag)))
           (or (vector? sel-frag)
               (map? sel-frag)
               (set? sel-frag)) (eval-selector sel-frag)
           (symbol? sel-frag) (if [resolved-var (resolve-enlive-var sel-frag)]
                                 resolved-var
                                 sel-frag)
            :else sel-frag)))
   (cond
    (vector? sel) []
    (set? sel) #{}
    (map? sel) {}
    :else []) sel))

Feel free to clone kioo and see if it works. If that doesn't help then the maintainer would have to step in and offer a suggestion.