In Clojure the answer is [2 2]. A beginner might guess [2 2] or [2 3]. Both are reasonable guesses, so a beginner needs to be quite careful!
But that isn't particularly interesting, because beginners always have to be quite careful. When you are learning any technology, you are a beginner once and experienced ever after. Tool design should optimize for the experienced practitioner. Immutability removes an enormous source of complexity from programs, so where it is feasible it is often desirable.
(let [x 1] [(inc x) (inc x)])
In Clojure the answer is [2 2]. A beginner might guess [2 2] or [2 3]. Both are reasonable guesses, so a beginner needs to be quite careful!
But that isn't particularly interesting, because beginners always have to be quite careful. When you are learning any technology, you are a beginner once and experienced ever after. Tool design should optimize for the experienced practitioner. Immutability removes an enormous source of complexity from programs, so where it is feasible it is often desirable.