Chris Cain:
Instead of having a "dead flag", you could swap ( http://dlang.org/phobos/std_algorithm.html#swap ) the dying particle with the last particle in the list and then decrement the list's length.
If the array is long you are accessing a cold part of it to swap with the end.
By default (using the default GC and everything), D does not reallocate a dynamic array every time you change the length (even increasing it), so this will still be okay with allocations.
The situation is a little more complex, there is a capacity field that I think is kept in a cold place of the array, it's also cached, but only if you append to just one array, etc.
Bye, bearophile
