+

(+ <z1> …) returns the sum of its arguments. No argument may be supplied, in that case + will return 0.

If any argument is inexact, then the result will also be inexact.

Example:

[1] (+)
0
[2] (+ 1)
1
[3] (+ 2 3)
5
[4] (exact? (+ 2 3.0))
#f
[5]