Duncan Coutts wrote:
modify :: k -> Map k e -> (e, Maybe e -> Map k e)
so it's a lookup that returns the element at k and also a continuation
that lets you rebuild a new map with an altered element. I guess that
doesn't account for the element not existing. There's probably a
generalisation that does.
isn't it just adding the necessary Maybe?:
modify :: k -> Map k e -> (Maybe e, Maybe e -> Map k e)
?
-Isaac
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