I don't consider assignment to have a "side effect". Assignment is the effect. It might have a side effect if I'm working with a tied variable, I guess, but that's out somewhere else.

Another difference between for and map is what happens when the BLOCK modifies the array that it's iterating over. 

my @x;

# loops once
@x = qw( x );
map { push @x, 'x' } @x;

# loops forever
@x = qw( x );
push @x, 'x' for @x;

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In reply to Re^3: map in void context by kyle
in thread map in void context by dharanivasan

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