use update instead of assoc

can u explain why please?

user=> (def a (atom {:b [1]}))
#'user/a
user=> @a
{:b [1]}
user=> (swap! a update :b conj 2)
{:b [1 2]}

Because it’s not atomic if you do two atom operations- @ and swap!

That’s a race condition

With a single op it’s atomic

@U1Z392WMQ thanks for explanation. @U050ECB92 do you mean I should remove the dereference character from there?

Yes. You’re deferencing and swapping - and swap always passes the derefenced value to the function passed in

gotcha, thanks

Just a different interface for a similar behavior. update takes a function of the current value, assoc takes a new value to replace the existing one with

Given a map m, (update m :clicks inc) is equivalent to (assoc m :clicks (inc (:clicks m))) Both are correct but the former is arguably easier to read My rule of thumb is: if the new value depends on the old value (like didibus said), update probably makes more sense, otherwise use assoc