Gaby described how to obtain the type of a functor. A functor is an "unapplied" domain constructor. A domain constructor is an expression. So for example Complex Integer is a domain constructor. Complex is the functor.

Example Complex

)boot getConstructorSignature 'Complex

(EVAL-WHEN (EVAL LOAD)
  (PROG () (RETURN (|getConstructorSignature| '|Complex|))))
Value = ((|Join| (|ComplexCategory| |#1|)
                 (CATEGORY |package|
                  (IF (|has| |#1| (|OpenMath|))
                      (ATTRIBUTE (|OpenMath|))
                      |noBranch|)))
         (|CommutativeRing|))
--)boot getConstructorSignature('Complex).target

)boot first getConstructorSignature('Complex)

(EVAL-WHEN (EVAL LOAD)
  (PROG () (RETURN (CAR (|getConstructorSignature| '|Complex|)))))
Value = (|Join| (|ComplexCategory| |#1|)
                (CATEGORY |package|
                 (IF (|has| |#1| (|OpenMath|))
                     (ATTRIBUTE (|OpenMath|))
                     |noBranch|)))
--)boot getConstructorSignature('Complex).source

)boot first rest getConstructorSignature('Complex)

(EVAL-WHEN (EVAL LOAD)
  (PROG () (RETURN (CAR (CDR (|getConstructorSignature| '|Complex|))))))
Value = (|CommutativeRing|)