[Haskell-cafe] Re: Layered maps

Thomas DuBuisson wrote:

On Fri, Oct 8, 2010 at 2:23 PM, Alex Rozenshteyn wrote:

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Does there exist a library which allows me to have maps whose elements are maps whose elements ... with a convenient syntax. The containers library can do this already - there are no constraints on the elements of a Map. For example:

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type TripleNestedMap a = Map Int (Map Char (Map String a))

But this is rather silly as you can just do:

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type MapOfTriples a = Map (Int ,Char, String) a

for most uses.

True, but I think this:

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Alternatively, does there exist a library like Data.Tree where forests are sets rather than lists?

suggests that the OP wants something different, rather like import Data.Map data MapTree a = Leaf | Node (Map a (MapTree a)) I don't know if somebody wrote a library around such a type. Alex, could you give an example for what would be 'a convenient syntax' for such a type? What operations do you think should be available to make using it convenient? Cheers Ben