Good point about the use of null. That would be a good choice for an Array where null is not a naturally-occurring element. For an array of class instances though, it just might. Perhaps in that case it would be better to use -1 and in the case of an Array of int, Number, or the like to use null. Thanks for the suggestion!

Though I’m not sure of your conclusion.
Why is step C required? Are you talking about
an array with multiple undefined values?
You only need to fill “undefined” value. so when you remove the first element, you must fill that one only to get back the whole dense array. tamarin is doing the iterative work to transfert all values (until first undefined) to the dense part.

as for the “-1″ value, it can also be “null”. since null is a valid atom for tamarin, you can use null for filling holes.
If you have an array with 75% of valid values in it, I would suggest filling all others with “null” values to make your array faster.
If you read my next article you’ll see flash is allocating memory in block of 4K, so filing empty values or nulll-initialisation of values is not heavy on memory, it will only take some more process at the beginning. http://jpauclair.wordpress.com/2009/12/05/tamarin-part-ii-more-on-array-and-vector/