Why is it being counted? return true in one case and false in another?

Question

Clojure 1.2.0
user=> (def x (repeat 10 1))
#'user/x
user=> (counted? x)
false
user=> (def x (list 1 2 3))
#'user/x
user=> (counted? x)
true
user=>

+3

yalis Mar 19 '11 at 18:36

1 answer

dbyrne · Accepted Answer · 2011-03-19T18:45:08+0000

Obviously, there is no way to know how many elements are in a lazy sequence until this sequence is evaluated.

counted?returns true for any class that implements the interface clojure.lang.Counted.