Edit Question - KnowledgeHub

Title Body

Python has a built in function sum , which is effectively equivalent to: def sum2(iterable, start=0): return start + reduce(operator.add, iterable) for all types of parameters except strings. It works for numbers and lists, for example: sum([1,2,3], 0) = sum2([1,2,3],0) = 6 #Note: 0 is the default value for start, but I include it for clarity sum({888:1}, 0) = sum2({888:1},0) = 888 Why were strings specially left out? sum( ['foo','bar'], '') # TypeError: sum() can't sum strings [use ''.join(seq) instead] sum2(['foo','bar'], '') = 'foobar' I seem to remember discussions in the Python list for the reason, so an explanation or a link to a thread explaining it would be fine. Edit : I am aware that the standard way is to do "".join . My question is why the option of using sum for strings was banned, and no banning was there for, say, lists. Edit 2 : Although I believe this is not needed given all the good answers I got, the question is: Why does sum work on an iterable containing numbers or an iterable containing lists but not an iterable containing strings?

Tags (comma-separated) Cancel