[clean-list] uniqueness question

[Vag Vagoff]

It is very convenient to use

     class (+) infixl 6 a :: !*a !a -> .a

for example,

     instance + BigInt where (+) a b = add_inplace_UB_B a b

thus,

     fn1 :: *a .a -> *a | + a
     fn2 :: v:a u:a -> v:a | SomeClass a , [v <= u]

are quite possible in real programs.