Type inferrence problem

Hugs (Version Nov 2002) cannot handle the following function definition:
 
f :: Ord a => Int -> [a] -> [a]
f 0 xs       = xs
f _ []       = []
f n (x:y:zs) | x > y     = y : (f (n - 1) x:zs)
             | otherwise = x : (f (n - 1) y:zs)
 
 
Hugs generates the message:
 
ERROR "C:\Program Files\Hugs98\Henk-Jan\error.hs":2 - Inferred type is not general enough
*** Expression    : f
*** Expected type : Ord a => Int -> [a] -> [a]
*** Inferred type : Ord [a] => Int -> [[a]] -> [[a]]
 
It seems to me that this is a bug in the inferrence mechanism.
 
Henk-Jan.
 
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