I believe* that the reason is nothing to do with the void context. for is optimised to treat the range operator as an iterator, by which I mean it doesn't generate a list of 1_000_000 scalars, it simply supplies the next incremented value as $_ for each iteration.

map on the other hand doesn't have this optimisation and so a very large list is generated as the input to map. This is what (briefly) consumes the memory. For short ranges this isn't a problem, but for larger ones, it's worth avoiding.

* I'm fairly confident that this is the case, but it is acquired knowledge rather than something I can point my finger at the sources and say "There".

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail

In reply to Re: Re^3: When would you choose foreach instead of map? by BrowserUk
in thread When would you choose foreach instead of map? by jpfarmer

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