Cons

s-expression

cons cell

car cdr

cons가 아닌 것은 아톰

(atom (cons 1 2))
;;=>  NIL

(consp '())
;;=> NIL

(consp '(1))
;;=> T

(consp '(1 . 2))
;;=> T

(consp '(1 2))
;;=> T

(type-of '())
;;=> NULL
(typep '() 'atom)
;;=> T

(type-of '(1))
;;=> CONS


(typep '() 'cons)
;;=> NIL
(typep '() 'list)
;;=> T

(typep '(1) 'cons)
;;=> T
(typep '(1) 'list)
;;=> T

(typep '(1 . 2) 'cons)
;;=> T
(typep '(1 . 2) 'list)
;;=> T

짚고 넘어가기

  • car / cdr
  • first / rest
  • cons
  • `consp