map/filter/reduce/lambda opinions and background unscientific mini-survey

Tom Anderson twic at
Tue Jul 5 15:01:04 CEST 2005

On Mon, 4 Jul 2005, George Sakkis wrote:

> "Tom Anderson" <twic at> wrote:
>> I'll just chip in and say i'd quite like a flatten(), too; at the moment,
>> i have one like this:
>> def flatten(ll):
>>   return reduce(lambda a, l: a.extend(l), ll, [])
> This doesn't work; a.extend() returns None, not the extended list a:

Ah, no, very good, i was hoping someone would notice that. Well done.

I think my lambda looks more like lambda a, b: a + b, but i realised the 
other day that extend could make it more efficient, and didn't think it 
through properly.


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