October 2016 1Liner 1HaskellADay problem and solutions

• October 21st, 2016:
  You have l1 :: [(v, [(k, x)])]
  You need the transformation l2 :: [(k, [(v, x)])]
  Redistribute v and k in one line
  Props for elegance
• Francisco T @aiceou redist xs = fromListWith (++) $ concat $ (map f xs) where f (a,ys) = map (\(x,y) -> (x,[(a,y)])) ys ... but k has to be 'Ord'