[Haskell-cafe] Control.bimap?

[Clark Gaebel]

Also,
http://hackage.haskell.org/packages/archive/bifunctors/3.0/doc/html/Data-Bifunctor.html


On Wed, Dec 12, 2012 at 4:12 PM, Clark Gaebel <cgaebel at uwaterloo.ca> wrote:

>
> 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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