while for and foreach as keywords are interchangible, in my opinion, in perl, foreach-style loops are better for most list processing tasks.

foreach my $thing(@things){
    process($thing);
}
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But sometimes it's more intuitive to use for(;;) when you are processing only, say, every third item in a list.

for(my $i=0;$i < scalar(@things); $i += 3){
    process($things[$i]);
}
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