Predicate of a Conditional

scheme.rkt

(define (seval-if sexp env)
  (let ((test (if-test sexp))
        (then-clause (if-then-clause sexp))
        (else-clause (if-else-clause sexp)))
    (if (actual-value test env)
        (seval then-clause env) 
        (seval else-clause env))))