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To: python-list@python.org
From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: sum works in sequences (Python 3)
Date: Wed, 19 Sep 2012 14:49:45 -0400
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Xref: csiph.com comp.lang.python:29518

On 9/19/2012 11:07 AM, Alister wrote:

> Summation is a mathematical function that works on numbers
> Concatenation is the process of appending 1 string to another
>
> although they are not related to each other they do share the same
> operator(+) which is the cause of confusion.

If one represents counts in unary, as a sequence or tally of 1s (or 
other markers indicating 'successor' or 'increment'), then count 
addition is sequence concatenation. I think Guido got it right.

It happens that when the members of all sequences are identical, there 
is a much more compact exponential place value notation that enables 
more efficient addition and other operations. When not, other tricks are 
needed to avoid so much copying that an inherently O(N) operation 
balloons into an O(N*N) operation.

-- 
Terry Jan Reedy