Note also that there are two ways to write a map, viz map { block } list and map expression, list.

$ perl -le '
-> @arr = qw{a b c};
-> map { tr/[a-z]/[A-Z]/ } @arr;
-> print qq{@arr};'
A B C
$ perl -le '
-> @arr = qw{a b c};
-> map tr/[a-z]/[A-Z]/, @arr;
-> print qq{@arr};'
A B C
$
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Cheers,

JohnGG