On Wed, 19 Sep 2012 16:41:20 +0200, Franck Ditter wrote:
> Hello,
> I wonder why sum does not work on the string sequence in Python 3 :
>
>>>> sum((8,5,9,3))
> 25
>>>> sum([5,8,3,9,2])
> 27
>>>> sum('rtarze')
> TypeError: unsupported operand type(s) for +: 'int' and 'str'
>
> I naively thought that sum('abc') would expand to 'a'+'b'+'c'
> And the error message is somewhat cryptic...
>
> franck
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.
attempting to duck type this function would cause ambiguity for example
what would you expect from
sum ('a','b',3,4)
'ab34' or 'ab7' ?
even 'A' + 7 would return this error for same reason.
--
It is the nature of extreme self-lovers, as they will set an house on
fire,
and it were but to roast their eggs.
-- Francis Bacon
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