Documented in perldoc -f sort:

Warning: syntactical care is required when sorting the list returned from a function. If you want to sort the list returned by the function call find_records(@key), you can use:

my @contact = sort { $a cmp $b } find_records @key;
my @contact = sort +find_records(@key);
my @contact = sort &find_records(@key);
my @contact = sort(find_records(@key));
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If instead you want to sort the array @key with the comparison routine find_records() then you can use:

my @contact = sort { find_records() } @key;
my @contact = sort find_records(@key);
my @contact = sort(find_records @key);
my @contact = sort(find_records (@key));
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