Ah Ha! Of course. I guess that I should have thought of that. Anyway, after trying several different separators (',', ' ', '_', '-', '.', '0') and even trying padding with zeroes (01, 02, ..., 08), the only solution that works well is no separator which makes it more difficult when we move to permutations of 10 or more things. Although from blssu's results below it looks as though some of this was fixed in perl 5.8 (I'm still limping along at 5.6.1).
As I'm now (attempting to) learn C, maybe this is obvious to me because it's a common idiom in C: use letters instead. You can use the ord function to get a mapping between the letters and the numbers, and you can even normalize the set [a-z] -> [0-25] by subtracting ord("a"). Also, you wouldn't have to change much else (from what I can see, anyways). For instance: 
$n = 8;  @n = (1..$n);

[download]
becomes 
$n = ord("a")+8; @n = ("a"..$n);

[download]
Of course, this all assumes that you don't do many explicit aritmetic calculations on your set of permutations. If you do, the repeated calls to ord and char my be prohibitive.

thor

In reply to Re: Re: Re: constructing large hashes by thor
in thread constructing large hashes by duelafn

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