At 08:57 AM 10/21/03 -0500, Skip Montanaro wrote:
>> [Alex measures speed improvements]
Guido> Great! This is a plus for iterator comprehensions (we need a Guido> better term BTW).
Here's an alternate suggestion. Instead of inventing new syntax, why not change the semantics of list comprehensions to be lazy? They haven't been in use that long, and while they are popular, the semantic tweakage would probably cause minimal disruption. In situations where laziness wasn't wanted, the most that a particular use would have to change (I think) is to pass it to list().
If you make it a list that's lazy, it doesn't lose the memory allocation overhead for the list. If I understand Alex's benchmarks, making a lazy list would end up being *slower* than list comprehension is now. I previously proposed a different solution earlier in this thread, where you get a pseudo-list that, if iterated, runs the underlying generator function. But there were issues with possible side-effects (not to mention reiterability) of the underlying iterator on which the comprehension was based.