Array Slicing Trouble

For example I have array of size 10.
Then I need to combine array[5] and array[6], by simple add (or whatever I want to use).

So, array[1],array[2],array[3],array[4] wont be touched,
but array[5] becomes array[5] + array[6].

then, all the other array indexes get 1 step 'backwards':
array[6] = array[7]
array[7] = array[8]
array[8] = array[9]

Is this possible with slicing? Whatever fast way works fine.. Id hate to use for loops for this. The array size can be left untouched though (no problem there)

Hi,

No, this really requires 'array concatenation' which you can't do (yet) so you'll need to use a loop.

I have been thinking of adding this, though, possibly with syntax something like:

a[5]:+a[6]
a=a[1..5,7..]

Please add it, please oh please oh please oh pleeeease!

Thanks