list comprehension question

[Lie Ryan]

Steven D'Aprano wrote:
>> "If you’ve got the stomach for it, list comprehensions can be nested.
>> They are a powerful tool but – like all powerful tools – they need to be
>> used carefully, if at all."
> 
> How does this discourage the use of list comprehensions? At most, it 
> warns that complicated list comps are tricky. Complicated *anything* are 
> tricky.
> 
> 
>> and
>>
>> "In real world, you should prefer builtin functions to complex flow
>> statements."
> 
> That's ridiculous. The example given is a special case. That's like 
> saying "Loops are hard, so in the real world, if you want a loop, find a 
> builtin function that does what you want instead."
> 
> What's the "builtin function" we're supposed to prefer over a "complex 
> flow statement" like this?
> 
> # split text into word fragments of length <= 3
> sentence = "a sentence is a series of words"
> new = [word[i:i+3] for word in sentence.split() for i in range(0, len(word), 3)]

I often found list comprehension *more* readable than the equivalent 
for-loop because of its density. Seeing complex for-loop requires one 
step of thinking for each line, but in list comprehension I can skip 
some of the steps because I know what list comprehension would roughly 
look like.

i.e.

when I process this:

lst = []              #1
for i in range(10):   #2
     lst.append(i)     #3

I do 3 steps of thinking for each line

but seeing this is only one step, since I know it is going to create new 
list (skipping step #1) and I know i will be appended to that list 
(skipping step #3)