the name 'xor' can be misleading

[vvvvalvalval]

Small nitpick on the 'xor' name:

In this library, the semantics of xor is "matches exactly one spec".

However, the commonly accepted meaning of the XOR operator (in math and CompSci) is boolean addition, which actually means "an odd number of those are true" (not "exactly one of those is true", except for the 2-arity case of course).

I think one-of would be a better name. If it's too late, maybe document it?

[gfredericks]

this is a good criticism.

one thing it's not too late to do is make an alias and deprecate the old name.

Not sure how I feel about one-of, it might be easy to interpret the same way as s/or. exactly-one-of is pretty long though.

[vvvvalvalval]

Let's not optimize prematurely for concision :) (not until experience shows people use it a lot, at which point we can always think of a shorter alias)

That be said, I can suggest one-match as another shorter name

[gfredericks]

I just remembered that it should be fine to break things as long as clojure.spec is still breaking things. So I'll just rename it.

[muhuk]

I'd read one-of might match one or more.

How about just-one ?

[aaroncummings]

I think the term 'one-hot' (from logic design) might best represent the intent. See https://en.wikipedia.org/wiki/One-hot for the background.