[Haskell-beginners] a problem with maps

[Ertugrul Soeylemez]

Dennis Raddle <dennis.raddle at gmail.com> wrote:

> mapOutList :: Ord k => [(k,a)] -> Mpa k [a]
> mapOutList list = M.fromList $ map (second (: [])) list

I'm not sure that this really does what you want.  Rather something like
this:

    fromAmbList :: Ord k => [(k, a)] -> Map k [a]
    fromAmbList = M.fromListWith (++) . map (second pure)


Greets,
Ertugrul


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