> From my point of view, Stef, implementing #<- with a completely 
> different meaning would be confusing.

This is really a personal preference. From my own point of view, I do 
not see why a formal symmetry in a method selector should imply a 
symmetry in the method semantics.

For example, would you implement #\ in Number, so that 2\3 is 3/2 ?

Anyway my actual point is that what you propose here is that #<- would 
be implemented in Object, making it unavailable to all classes in the 
system.

This represents a very important cost for no new semantics, just 
syntactic sugar.

Stef