defmostly

Multimethod-like dispatch leveraging Clojure Spec.

Clojure's multimethods (defmulti) require the dispatch function to produce an exact match for one of the registered defmethods.

defmostly takes a looser approach that levarages specs and their specificity.

Specificity.. What is it? Currently a recursive count of spec predecates. For example (s/def ::user (s/keys :req-un [::id ::email])) has a specificity of 2.

During definition defmostly determines the specificity of the passed in spec.

During dispatch defmostly reduces over the specs, narrowest (highest specificity) first, running s/valid? with passed argument. Upon the first valid result, it shortcircuits and invokes the argument with the registered function.

defmostly is an idea-sketch and should not be used in production.

Usage

(nsmy-ns
(:require [den1k.defmostly :refer [defmostly]]))
(defmostlyauth::logged-out-user
[user]
(println:login! user))
(defmostlyauth::logged-in-user
[user]
(println:logout! user))
(auth {:db/id #uuid "84a4afff-8816-401f-a09e-8d4325801f86"})
;=> :login! #:db{:id #uuid "84a4afff-8816-401f-a09e-8d4325801f86"}
(auth {:db/id #uuid "84a4afff-8816-401f-a09e-8d4325801f86":user/session {:session/key"foo"}})
;=> :logout! {:db/id #uuid "712fcc62-77e6-4811-86f9-6db8528f69eb"; :user/session #:session{:key foo}}

Todo

• CLJC compatability
• benchmarks & performance improvements

License

Copyright © 2019 Dennis Heihoff

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.