> '(+ 1 2)
'(+ 1 2)
> (car '(+ 1 2))
'+
> (car (cons + (list 1 2)))
#<procedure:+>
> '(+ 1 2)
'(+ 1 2)
> (eval '(+ 1 2))
3

> (eval (let ((a 3) (b 4)) (list + a b)))
7
> (eval (let ((a 3) (b 4)) `(+ ,a ,b)))
7
>