genexp performance problem?

[Fredrik Lundh]

Giovanni Bajo wrote:

> I found this strange:
> 
> python -mtimeit "sum(int(L) for L in xrange(3000))"
> 100 loops, best of 3: 5.04 msec per loop
> 
> python -mtimeit "import itertools; sum(itertools.imap(int, xrange(3000)))"
> 100 loops, best of 3: 3.6 msec per loop
> 
> I thought the two constructs could achieve the same speed.

hint: how many times to the interpreter have to look up the names "int" 
and "L" in the two examples ?

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