Paths are left as paths, instead of trying to convert them to strings
or byte strings. Submodule path elements should be unquoted -- in the
same form as a `submod' form. All extra parts are submodule path elements,
never module paths or ".".
This library is used by Redex, which wants a `syntax'-like template
language, but for datum values instead of syntax objects. Using
`datum-case' and `datum' generates much less code. Redex uses
only a small part of the general functionality, so adding
`syntax/datum' could be overkill. It's implemented by generalizing
the `syntax-case' and `syntax' pattern matching and template
constructing code, though; it's not a lot of extra code, and it's
easiest to generalize completely. We may find other uses for
datum templates, too.
