Compile spec coercers

[ikitommi]

Spec are walked at runtime with st/coerce. As the specs SHOULD NOT CHANGE in production, we can precompile the coercers for faster processing.

With the given specs:

(require '[clojure.spec.alpha :as s])
(require '[spec-tools.core :as st])

(s/def :sku/id keyword?)
(s/def ::sku (s/keys :req-un [:sku/id]))
(s/def ::skus (s/coll-of ::sku :into []))

(s/def :photo/id int?)
(s/def ::photo (s/keys :req-un [:photo/id]))
(s/def ::photos (s/coll-of ::photo :into []))

(s/def ::data (s/keys :req-un [::skus ::photos]))

Compile coercers:

(def string->data (st/coercer ::data st/string-transformer))
(def json->data (st/coercer ::data st/json-transformer))

Apply them:

(string->data
  {:skus [{:id "123"}]
   :photos [{:id "123"}]})
; {:skus [{:id :123}]
;  :photos [{:id 123}]}

(json->data
  {:skus [{:id "123"}]
   :photos [{:id "123"}]})
; {:skus [{:id :123}]
;  :photos [{:id "123"}]}

Maybe even:

(let [[string->data json->data] (st/coercers ::data [st/string-transformer st/json-transformer]))]
     ....)

Caveat: spec registration is imperative, one can re-register any spec at any time, so the compiled results can be out-dated. Such is life in the land of lisp.