;; also known as <*> or ap
(bind-func apply:[ADOption{!b}*,ADOption{[!b,!a]*}*,ADOption{!a}*]*
(lambda (F1 F2)
(ADSome$ F1 (f)
(ADSome$ F2 (x)
(ADSome (f x))
(ADNone))
(ADNone))))