return [result] →|

result — a form; evaluated. The default is nil.

Returns, as if by return-from, from the block named nil.

(block nil (return) 1) → NIL 
(block nil (return 1) 2) → 1 
(block nil (return (values 1 2)) 3) → 1, 2 
(block nil (block alpha (return 1) 2)) → 1 
(block alpha (block nil (return 1)) 2) → 2 
(block nil (block nil (return 1) 2)) → 1

block, return-from, Section 3.1 (Evaluation)

(return) ≡ (return-from nil) 
(return form) ≡ (return-from nil form)

The implicit blocks established by macros such as do are often named nil, so that return can be used to exit from such forms.