use Sort::Key qw(multikeysorter);
my @spec = ( { KeyName => 'SALARY',
               SortType => 'number' },
             { KeyName => 'FIRST_NAME',
               SortType => 'string' } );

my @keys = map $_->{KeyName} @spec;
my @types = map $_->{SortType} @spec;

my $sorter = multikeysorter(sub { @{$_}{@keys} }, @types);

my @sorted_data = $sorter->(@data);
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