Re: [Haskell-cafe] Efficient functional idiom for histogram

[Malcolm Wallace]

In an imperative language like Python, I'd use a dictionary as an
accumulator - something like

   for el in input:
       accums[i] = accums.get(i, 0) + 1

Haskell has efficient dictionary structures too, e.g. Data.Map

  List.foldl' (\m x-> Map.insertWith' (+) x 1 m) Map.empty

Regards,
    Malcolm

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