addition (juxtaposition) unhelpful for some cases with a clear interpretation

[RobinHankin]

Look at this:

> a <- rfree(10,3)
> a
 [1] c^-2.a^3      a^2.c         b^2.c^2.b^-1  a.c^-1        c^5          
 [6] b^2.c^3.b     c^3.a^-4      c^3.b^4       b^-2.a^3.b^-1 a^-2.c^-1.b^3
> a+'z'
Error in Ops.free(a, "z") : <free> + <non-free> is not defined 
> a+as.free('z')
 [1] c^-2.a^3.z      a^2.c.z         b^2.c^2.b^-1.z  a.c^-1.z       
 [5] c^5.z           b^2.c^3.b.z     c^3.a^-4.z      c^3.b^4.z      
 [9] b^-2.a^3.b^-1.z a^-2.c^-1.b^3.z
> 

In the above, a+'z' has a natural interpretation but this is not accepted. One has to coerce as in the second addition to make it work. I guess something like 'z'+a would also have a natural interpretation but this idiom would require S4 methods to work.

[RobinHankin]

I do not think this should be fixed. It is reasonable to force the user to coerce the second addend to a freegroup object.