?: is if-then-else: it picks its first branch when the test is yes, the second when no.

?:((gth 3 5) 10 20) is 20.

?! negates a loobean - yes becomes no.

?!(=(3 3)) is %.n.

irregular forms:

!a is ?!(a)

.= tests two nouns for equality, giving a loobean.

.=(3 3) is %.y, and .=(3 4) is %.n.

irregular forms:

=(a b) is .=(a b)