[Haskell-cafe] Histogram creation

[Alexey Khudyakov]

Hello!

I'm tryig to write efficient code for creating histograms. I have following
requirements for it:

1. O(1) element insertion
2. No reallocations. Thus in place updates are needed.


accumArray won't go because I need to fill a lot of histograms (hundrends) from
vely long list of data (possibly millions of elements) and it will traverse
input data for each histogram.

It seems that I need to use mutable array and/or ST monad or something else.
Sadly both of them are tricky and difficult to understand. So good examples or
any other ideas greatly appreciated.

-- 
  Alexey Khudyakov