Now: if I have a couple of thousand of these Instances, created with the same Attributes value, as in:
 
a = Attributes ["a","bc"]
i0000 = Instance a [1,2]
i0001 = Instance a [1,1]
...
i7896 = Instance a [2,1]
 
can I be assured that there are not thousands of actual copies of a but that they simply have a pointer to a ? I'm interested in the answer for both ghc (compiled/interpreted) as interpreted Hugs. 
Yes for GHC: you'll only get one copy of 'a'.
 
Simon