MathGroup Archive 2004

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Re: Re: Sequential evaluation of lists

The evaluation order is an internal property of Mathematica's function. 
It has strong effect on their efficiency (memory management and the way 
internal data is stored). However, I think that partial control is 
available if you Reverse the input before evaluation, say

János wrote:

>It would be nice to have all List manipulation functions have an option 
>Direction->Left or Direction->Right, just as Limit has +1 or -1. I even 
>would like functional programming functions like Map or Apply have this 
>option. Any seesaw type operation modeling would greatly benefit from 
>it and nature has many.
>On Dec 22, 2004, at 4:53 AM, Ray Koopman wrote:
>>When I first started using Mathematica (v2), one of the features that
>>I found rather surprising is its sequential evaluation of lists, as in
>>In[1]:= x = 0; {x++,x++,x++}
>>Out[1]= {0,1,2}
>>I had expected a warning that such code should be avoided because
>>it presumed sequential evaluation, which could not be guaranteed,
>>and a recommendation to treat list elements as being evaluated in
>>parallel -- if not simultaneously then in no particular order.
>>However, so far I have found no exception to sequential evaluation
>>and no mention of it in any documentation. Have I missed something?

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