[Haskell-cafe] Control.bimap?

[Clark Gaebel]

http://hackage.haskell.org/packages/archive/categories/0.59/doc/html/Control-Categorical-Bifunctor.html


On Wed, Dec 12, 2012 at 3:54 PM, Gregory Guthrie <guthrie at mum.edu> wrote:

> I found a nice idiom for a graph algorithm where the pairs of nodes
> representing links could be merged into node lists by something like:****
>
>     ns = nub $ map fst  g    --head nodes****
>
>     ne = nub $ map snd g   -- tail nodes****
>
> ** **
>
> And found a nicer approach:****
>
>    (ns,ne) = (nub***nub) unzip g****
>
> Or perhaps:****
>
>    (ns.ne) = bimap nub nub $ unzip g    -- from Control.Bifunctor ****
>
> ** **
>
> The SO reference I saw described bimap as a way to map a function over a
> pair, and it seemed like a great match, but I cannot find the bimap
> function, and cabal reports no package Control.Bifunctor.****
>
> ??****
>
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>
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