lib/Module.pm
lib/Helper.pm

##</code><code>##

WriteMakefile( #...
'PM' => {
    'lib/Data.pm'     => '$(INST_LIBDIR)/Data.pm',
    'lib/Scalar.pm'   => '$(INST_LIBDIR)/Data/Scalar.pm',
    'lib/Array.pm'    => '$(INST_LIBDIR)/Data/Array.pm',
    'lib/Hash.pm'     => '$(INST_LIBDIR)/Data/Hash.pm',
    'lib/Function.pm' => '$(INST_LIBDIR)/Data/Function.pm',
    },
#...
);