Arrays in Rev (long)

[Brian Yennie]

> Even more interesting, addressing the keys of the array by string name 
> rather than integer key location, doesn't increase the time 
> appreciably (then again, I imagine even the element location is a 
> string in Transcript.) -

That's because they're associative arrays (as opposed to numeric)... 
not even a Rev thing- basically it means that every key is located by 
using a numeric hash on it's key value, but most importantly, they are 
usually implemented by using some sort of balanced tree structure in 
memory rather than a sequential block of memory. Essentially what you 
get is binary search for your data: if you have 2^N keys it takes at 
most N hops to find your data because the nodes of the tree are sorted 
and balanced. For the curious or bored, try googling "red black tree 
algorithm". So for a 10,000 key array you'll get anything you want in 
between 1 - 14  (2^14 =~ 16,000) quick hops.

If Rev allowed you to pick a numeric array (as opposed to an 
associative one) then you'd always get your data in one lookup with 
numeric keys, but keep in mind that the two are pretty different 
beasts. I suppose it would be handy to be able to have a numeric array 
and squirrel it away inside of an associative array, but you'd have to 
do some really serious pounding to make 10 pointer lookups add up to 
any bothersome speed problem...

FWIW,
Brian