Why + (or *) act different for than - (or /) with zero arguments?

Question

When you call + with zero arguments

user=> (+)
0

I get 0 because it is invariant element to +. It works similar for *

user=> (*)
1

Why this does not work for - and / ?

user=> (-)
ArityException Wrong number of args (0) passed to: core/-  clojure.lang.AFn.throwArity (AFn.java:429)

user=> (/)
ArityException Wrong number of args (0) passed to: core//  clojure.lang.AFn.throwArity (AFn.java:429)

Answer 1

Note that - and / work differently when they are given a single argument: (- x 0) is different from (- x). The same for (/ x 1) and (/ x). The practical argument for + and * is that when your arguments may not be known beforehand, you can just apply or reduce over a list (possibly empty). The same is not true for division and negation, because you seldom need:

(apply / list)

You at least have one argument:

#(apply / (cons % list))

This is not authoritative, just a guess.