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3 points by pg 5908 days ago | link | parent

What do you do if you want to maintain a list of strings sorted according to their length?


4 points by raymyers 5908 days ago | link

If I wanted to keep using the Ord type-class for comparison, I might use a container type, like this:

    data Elem = Elem String deriving (Show, Eq)
    instance Ord Elem where
        Elem x < Elem y = length x < length y
    
    tree1 = insert (Elem "Some string") Empty
    tree2 = remove (Elem "Some string") tree1
If I really wanted to pass in the comparison function, I would have to change my code slightly. See: "A More Faithful Translation" (http://ray.codezen.org/wiki/doku.php?id=binary-search-tree).

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