[Haskell-cafe] Re: (flawed?) benchmark : sort
ndmitchell at gmail.com
Mon Mar 10 04:27:42 EDT 2008
> 2) What does it do with duplicate elements in the list? I expect it deletes
> them. To avoid this, you'd need to use something like fromListWith, keeping
> track of how many duplicates there are, and expanding at the end.
That would be wrong. Consider:
data Foo = Foo Int Int
instance Ord Foo where
compare (Foo a _) (Foo b _) = compare a b
sort [Foo 1 2, Foo 1 -2] must return the original list back, in that
order. You cannot delete things and duplicate them later. To guarantee
the ordering you must also do other stuff.
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