symbolp

symbolp Function

Syntax:

symbolp object → generalized-boolean

Arguments and Values:

object—an object.

generalized-boolean—a generalized boolean.

Description:

Returns true if object is of type symbol; otherwise, returns false.

Examples:

(symbolp ’elephant) → true 
(symbolp 12) → false 
(symbolp nil) → true 
(symbolp ’()) → true 
(symbolp :test) → true 
(symbolp "hello") → false 

See Also:

keywordp, symbol, typep

Notes:

(symbolp object) ≡ (typep object ’symbol)

Expanded Reference: symbolp

symbolp returns true if the object is a symbol, and false otherwise.

(symbolp 'hello)
=> T
(symbolp 'car)
=> T
(symbolp 42)
=> NIL
(symbolp "hello")
=> NIL
(symbolp #\A)
=> NIL

Both nil and t are symbols, even though they also serve as boolean values.

(symbolp nil)
=> T
(symbolp t)
=> T
(symbolp '())
=> T

Keywords are a subtype of symbol, so symbolp returns true for them.

(symbolp :test)
=> T
(symbolp :key)
=> T

symbolp returns false for all non-symbol objects, including lists, arrays, and functions.

(symbolp '(a b c))
=> NIL
(symbolp #(1 2 3))
=> NIL
(symbolp #'car)
=> NIL
(symbolp 3.14)
=> NIL

symbolp is equivalent to testing with typep for the type symbol.

(let ((x 'foo))
  (eq (symbolp x) (typep x 'symbol)))
=> T

(let ((x 42))
  (eq (symbolp x) (typep x 'symbol)))
=> T

symbolp is useful as a predicate with higher-order functions.

(remove-if-not #'symbolp '(a 1 b "c" :d 2 nil))
=> (A B :D NIL)