$ perl -l
use strict;
use warnings;
use locale;
use POSIX qw(locale_h);
print setlocale(LC_COLLATE,"de_DE") or die "foo? - $!\n";
("fähler"=~/^\w+$/) ? print "yup" : print "nope";
__END__
de_DE
nope

##</code><code>##

$ perl -l
use strict;
use warnings;
use utf8;
use locale;
use POSIX qw(locale_h);
print setlocale(LC_COLLATE,"de_DE") or die "foo? - $!\n";
("fähler"=~/^\w+$/) ? print "yup" : print "nope";
__END__
de_DE
nope

##</code><code>##

$ perl -l
use strict;
use warnings;
use utf8;
use locale;
use POSIX qw(locale_h);
print setlocale(LC_CTYPE,"de_DE") or die "foo? - $!\n";
("fähler"=~/^\w+$/) ? print "yup" : print "nope";
__END__
de_DE
yup