use strict;
use warnings;
use utf8;
use 5.010;
use Unicode::Normalize qw/NFKD/;
binmode STDOUT, ':encoding(UTF-8)';

sub frob {
    my $str = NFKD(shift);
    $str =~ s/\pM//g;
    $str =~ s/[^a-z-A-z0-9]/_/g;
    $str;
}

my $test = '&[]ÀÂÄàâäÇçÉÊÈËéêèëÏÌÎïìîÖÔÒöôòÜÛÙüûù?!;«»()" íóñÑáéóúÁÉÍÓÚ';
say frob $test;
__END__
[]AAAaaaCcEEEEeeeeIIIiiiOOOoooUUUuuu_________ionNaeouAEIOU