More seriously: `&.` and `.&` were rightly rejected since there are too many operators from `vector-space` which use operators beginning or ending with periods (which are used to indicate a point argument).  Sadly `vector-space` does not use any particular character to indicate scalar arguments, or we could steal it here.  What about `&^`?  Indicating that the first argument is a scalar and the second is a vector (well, or a point, but we can't win them all).  It also has the important-in-practice-if-not-in-theory benefit of being very easy to type.