3 ms·
> Is there a boolean predicate? Nope, because everything is a Boolean: NIL is false, and everything else is true.
by wtbob 10y ago
> Is there a boolean predicate?
Nope, because everything is a Boolean: NIL is false, and everything else is true.
- reikonomusha 10y agoThis is not quite precisely true. Everything is a generalized boolean, but not a boolean. Only T and NIL are of type BOOLEAN, which you can check with the function: (defun booleanp (x) (TYPEP x 'BOOLEAN))
- wtbob 10y agoYou're right, of course. Still, 'everything is a boolean' is close enough for government work:-)