use File::Spec::Functions qw(catdir catpath splitdir splitpath);

my ($volume, $directories, $file) = splitpath '//special/semantic//path/definition';

my @dir = splitdir $directories;

my $dir1 = catdir @dir;    # '/special/semantic/path'
my $dir2 = join '/', @dir; # '//special/semantic//path/'

my $path1 = catpath $volume, $dir1, $file; # '/special/semantic/path/definition'
my $path2 = catpath $volume, $dir2, $file; # '//special/semantic//path/definition'