Clojure Q&A - Recent questions tagged state

Why vswap is a macro instead of function like swap?

Sun, 04 May 2025 21:16:23 +0000

Why clojure.core/vswap is a macro with tag hint instead of a function called on clojure.lang.Volatile similar to clojure.core/swap?

What's an ideomatic way to manage state in a library?

Thu, 15 Feb 2024 12:46:36 +0000

I’m porting a JS library to clojure (and, potentially cljs), and I’m struggling with reasoning about local state. Imagine a scenario where you do RPC over websockets, and the server reply contextually depend on what the server had already sent you. You'd want to keep a local cache of the replies from the server, then.

In OOP world it's expected you incapsulate both the socket and the cache and provide the library users an interface that sends RPCs and transparently handles the cache population and pulling results from it. What would be the ideomatic way to do the same in clojure[-script]? Would I just return a map and expect my functions to take it as a first argument, returning the update state along with the rpc result?

Using the state instantiated by integrant init-key

Fri, 10 Nov 2023 07:09:07 +0000

hi folks, I am trying out Integrant library for state management. It's quite intuitive when it comes to managing (starting/halting) servers but I am confused regarding a certain use case.

I want to use integrant to instantiate and destroy an object. As usual I defined defmethods init-key and halt-key! . The problem is that I want a reference to the initialised object from init-key . Is there an idiomatic way to do this? Should I just have it available in an atom during init-key ?

(defmethod ig/init-key :my-space/my-key [_ opts]
  (let [account-id (:account-id opts)
        license-key (:license-key opts)]
    (MyObject. account-id license-key)))

;;How do I use the instantiated my object?