Why applying seq on a LazySeq returns ChunkedCons?

Question

(class (range 10))
;=> clojure.lang.LazySeq

(class (seq (range 10))
;=> clojure.lang.ChunkedCons

From my understanding, LazySeq is already an sequence, since:

(seq? (range 10))
;=> true

Answer 1

I guess I have an answer.

That's because using seq enforces the evaluation of the first element of LazySeq. Because seq returns nil when the collection & sequence is empty, it has to eval the element to decide that.

That's the exactly reason why rest is lazier than next, because (next s) is just (seq (rest s)).