maximumBy -is:exact -is:exact is:exact

maximumBy :: Foldable t => (a -> a -> Ordering) -> t a -> a
base Data.List Data.Foldable
The largest element of a non-empty structure with respect to the given comparison function.
maximumBy :: (a -> a -> Ordering) -> [a] -> a
base GHC.OldList
The maximumBy function takes a comparison function and a list and returns the greatest element of the list by the comparison function. The list must be finite and non-empty. We can use this to find the longest entry of a list: 
>>> maximumBy (\x y -> compare (length x) (length y)) ["Hello", "World", "!", "Longest", "bar"]
"Longest"