[R7RS base] Evaluates to datum.
(quote x) ⇒ x (quote (1 2 3)) ⇒ (1 2 3)
'x ⇒ x '(1 2 3) ⇒ (1 2 3)
Note: Literals are immutable. You’ll get an error
if you try to change, for example, a quoted pair with
or a literal string with
Mutability may be managed differently for each type, so some object
may not raise an error even if it appears in a part of literals
(it is often the case with user-defined class with read-time constructor,
see Read-time constructor. However, if you ever modify a literal
data, it is not guaranteed that the program runs correctly.