I was just reading a bit about the HQ9+ programming language ( http://esolangs.org/wiki/HQ9 ,  http://en.wikipedia.org/wiki/HQ9%2B and http://www.cliff.biffle.org/esoterica/hq9plus.html ), and it tells me something about a so called 'accumulator' which can be incremented, but not be accessed. Also, using the + doesn't manipulate the resu...
            
           
          
          
            
            In my quest to learn more F#, I tried to implement an "accumulator generator" as described by Paul Graham here. My best solution so far is completely dynamically typed:
open System
let acc (init:obj) : obj->obj=
  let state = ref init
  fun (x:obj) ->
    if (!state).GetType() = typeof<Int32>
       && x.GetType() = typeof<Int32> then
...
            
           
          
            
            An statistical accumulator allows one to perform incremental calculations. For instance, for computing the arithmetic mean of a stream of numbers given at arbitrary times one could make an object which keeps track of the current number of items given, n and their sum, sum. When one requests the mean, the object simply returns sum/n.
An ...
            
           
          
            
            Hi, I have a table like this one:
  SELECT value FROM table;
value
1
3
13
1
5
I would like to add an accumulator column, so that I have this result:
value  accumulated
1      1
3      4
13     17
1      18
5      23
How can I do this? What's the real name of what I want to do? Thanks
...