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[REBOL] Re: Millennium + 1 ...

From: rebol:techscribe at: 5-Jan-2001 14:55

Hi Gabriele, 0 is the privileged neutral position of the counter, where left and right meet. Everything in a block is either to the left or to the right of the counter. Because there can be no element located at the privileged counter position, therefore pick block 0 always returns none. If you change that you create a mess. You create the exact same mess, whether you introduce 0 as the first index to the right or to the left. Case 1) The current situation: + == to the right - == to the left 1 == first 2 == second 3 == third 4 == fourth +1 first index to the right -1 first index to the left +2 second index to the right -2 second index to the left +3 third index to the right -3 third index to the left +4 fourth index to the right -4 fourth index to the left and so on Case 2) Introduce 0 in either direction, and you lose the simplicity of the scheme, it becomes counter-intuitive: Case 2a) 0 as first index of block 0 == first 1 == second 2 == third 0 first index to the right -1 first index to the left +1 second index to the right -2 second index to the left +2 third index to the right -3 third index to the left +3 fourth index to the right -4 fourth index to the left You see it becomes confusing in two respects: second maps to 1, third maps to two, and what is two steps away to my right is +1, whereas what is also two steps but to my left -2 not -1, i.e. chaos. Case 2b) 0 as first index preceding the first element of the block (the first negative index, i.e. to the left) +1 first index to the right 0 first index to the left +2 second index to the right -1 second index to the left +3 third index to the right -2 third index to the left +4 fourth index to the right -3 fourth index to the left What did you win versus case 2a)? It's the same mess in reverse. This time the counter-intuitive stuff is happening on the left, in the negative area. But you are still mapping second to 1, and third to 2, and you what on the right is +2 on the left is now -1. You lose the symmetry. Hope this makes it a little clearer, Elan