not - boolean negation

(import (rnrs))                     ;R6RS
(import (rnrs base))                ;R6RS
(import (scheme r5rs))              ;R7RS
(import (scheme base))              ;R7RS

(not obj)

Returns #t if obj is false, and returns #f otherwise.

Returns a single value; a boolean.

(not #t)         =>  #f
(not 3)          =>  #f
(not (list 3))   =>  #f
(not #f)         =>  #t
(not '())        =>  #f
(not (list))     =>  #f
(not 'nil)       =>  #f

This procedure works the same in all Schemes.

This procedure can raise exceptions with the following condition types:

&assertion (R6RS)

The wrong number of arguments was passed.

R7RS

The assertions described above are errors. Implementations may signal an error, extend the procedure's domain of definition to include such arguments, or fail catastrophically.

if(3scm), boolean=?(3scm)

R4RS, IEEE Scheme, R5RS, R6RS, R7RS

The not function has been in Scheme since the beginning, even when it ran on MacLisp, and it was also present in LISP 1.5.

This page is part of the scheme-manpages project. It includes materials from the RnRS documents. More information can be found at https://weinholt.se/scheme/manpages/.