Why can I use a set as predicate in clojure?

I'm trying to remove an element from a list or set, like this:

(remove :Veronica (list :Veronica :Hailey))

It does not work, so, I went to remove documentation, that says I need to pass a predicate to the remove function. But the following code works:

(remove #{:foo} [:foo :bar])
(remove #{:foo} (list :foo :bar))

#{:foo} is a set. Why does it works?

Is a set a function?

Thanks

Why does the following

(remove :Veronica (list :Veronica :Hailey))
;(:Veronica :Hailey)

• run without errors?
• have no apparent effect?

---

A keyword such as :Veronica is a function accepting one argument, hence can be used as a predicate.

But ...

• It expects a map or set argument.
• It then looks itself up in the argument.

For example,

(:Veronica #{:Veronica})
;:Veronica

(:Veronica #{1 2 "Buckle my shoe"})
;nil

It also forgives useless arguments:

(:Veronica 4) ; 4 is not a map or set. 
;nil

So (:Veronica :Veronica) and (:Veronica :Hailey) are both nil, so the remove in

(remove :Veronica (list :Veronica :Hailey))

... accomplishes nothing, since the predicate always evaluates false(ish).

---

The other solutions explain why

(remove #{:foo} (list :foo :bar))

... has the effect you are looking for.