use Data::Dumper;

sub get_day_name { "hlaghlag"; }

print Dumper { map { $_ => get_day_name($_) } <DATA> };

__END__
foo
bar
baz
[download]

Compiled, ran, and gave the expected output for me. Perl 5.6.0, i686-linux.

Care to be more specific about "doesn't compile"?