(the module “in the middle” will be called twice)

Assuming the above is what is wanted (always an even number of calls), another approach (including efforts of others):

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -e
"my @modules = qw(zero one two three four five six seven);
 ;;
 while (@modules) {
   dd \@modules;
   my $n = $#modules / 2;
   print qq{@modules[ 0 .. $n ] -- @modules[ -$n-1 .. -1 ] \n\n};
   pop @modules;
   }
"
["zero", "one", "two", "three", "four", "five", "six", "seven"]
zero one two three -- four five six seven

["zero", "one", "two", "three", "four", "five", "six"]
zero one two three -- three four five six

["zero", "one", "two", "three", "four", "five"]
zero one two -- three four five

["zero", "one", "two", "three", "four"]
zero one two -- two three four

["zero", "one", "two", "three"]
zero one -- two three

["zero", "one", "two"]
zero one -- one two

["zero", "one"]
zero -- one

["zero"]
zero -- zero
[download]

Update: Added '--' marker to output to make partitioning clearer.