dot & cross binding powers + softbox workaround?

(%i1) (load(vect), load("soft_box.mac"))$

  (%i2) R : matrix([-1,0,0],[0,1,0],[0,0,1])$
  (%i3) e  : ([1,2,3] ~ [4,5,6]) . R;

  (%o3) [1,2,3] . [4,5,6]~matrix([-1,0,0],[0,1,0],[0,0,1])

Opps--this is bogus--Maxima ignores the parens?

  (%i4) args(e);
  (%o4) [[1,2,3],[4,5,6]~matrix([-1,0,0],[0,1,0],[0,0,1])]

  (%i5) express(e);
     ~ used with improper arguments: [4,5,6]matrix([-1,0,0],[0,1,0],[0,0,1])

A workaround using softbox:

  (%i6) softbox([1,2,3] ~ [4,5,6]) . R;
  (%o6) ([1,2,3]~[4,5,6]) . matrix([-1,0,0],[0,1,0],[0,0,1])

  (%i7) express(%);
  (%o7) matrix([3,6,-3])

--Barton