sum works in sequences (Python 3)

[Steven D'Aprano]

On Wed, 19 Sep 2012 15:07:04 +0000, 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. attempting to duck type
> this function would cause ambiguity for example what would you expect
> from
> 
> sum ('a','b',3,4)
> 
> 'ab34' or 'ab7' ?

Neither. I would expect sum to do exactly what the + operator does if 
given two incompatible arguments: raise an exception.

And in fact, that's exactly what it does.

py> sum ([1, 2, 'a'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'int' and 'str'



-- 
Steven