Support inheritance with maps

[ikitommi]

The awesome Plumatic Schema has concept of Abstract Map:

;; abstract-map (experimental) models "abstract classes" and "subclasses" with maps.
(require '[schema.experimental.abstract-map :as abstract-map])
(s/defschema Animal
  (abstract-map/abstract-map-schema
   :type
   {:name s/Str}))
(abstract-map/extend-schema Cat Animal [:cat] {:claws? s/Bool})
(abstract-map/extend-schema Dog Animal [:dog] {:barks? s/Bool})
(s/validate Cat {:type :cat :name "melvin" :claws? true})
(s/validate Animal {:type :cat :name "melvin" :claws? true})
(s/validate Animal {:type :dog :name "roofer" :barks? true})
(s/validate Animal {:type :cat :name "confused kitty" :barks? true})
;; RuntimeException: 
;; Value does not match schema: {:claws? missing-required-key, :barks? disallowed-key}

we could have that too.