use charnames ':full';
use Unicode::Normalize qw( NFC );

sub dump_str {
   print(charnames::viacode(ord($_)), "\n") for split //, $_[0];
}

$_ = "\N{LATIN SMALL LETTER A}\N{COMBINING DIAERESIS}";
dump_str($_);

print("--\n");

$_ = NFC($_);
dump_str($_);