name: "length"
module: "vectors"
section: "Predicates & Introspection"
aliases: ["count", "empty?"]
Vectors participate in Sema's generic collection functions:
```sema
(length [10 20 30]) ; => 3
(count [10 20 30]) ; => 3
(empty? []) ; => #t
(empty? [1]) ; => #f
```