parameter_types.clj

(defmulti foo identity)

(defmethod foo :foo [_] :foo)

(defmethod foo :bar [_] :bar)

(derive :foo-child :foo)
(derive :bar-child :bar)

(defn supported-parameter?
  "Predicate function that returns true if the parameter type is
  supported by grafter-server.  Supported parameters are types which
  supported either explicitly via the parse-parameter multimethod or
  through this multimethods type hierarchy."
  [p]
  (some (partial isa? p)
        (keys (methods foo))))

(defn parameter-type-chain
  "Interogates the parse-parameter multi-method and returns an ordered
  sequence representing the "
  [t]
  (when (supported-parameter? t)
    (let [ps (parents t)]
      (cons t (lazy-seq (mapcat parameter-type-chain ps))))))

(defn supported-parameter-types
  "Returns the set of currently supported parameter-types"
  []
  (->> (methods foo)
       keys
       (mapcat parameter-type-chain)
       set))

(comment 
  (parameter-type-chain :foo-child) ;; => (:foo-child :foo)

  )