In newLISP, true represents Boolean true:
> (if true (println "yes") (println "no"))
yes
"yes"
while nil represents Boolean false:
> (if nil (println "yes") (println "no"))
no
"no"
Like lua, 0 is evaluated true:
> (if 0 (println "yes") (println "no"))
yes
"yes"
empty list is also treated as false:
> (if '() (println "yes") (println "no"))
no
"no"
Check the following result:
> (if false (println "yes") (println "no"))
no
"no"
The reason is false is not defined here and its value is nil:
> false
nil
You can assign true to false and do some crazy thing:
> (let (false true) (if false (println "yes") (println "no")))
yes
"yes"