Btw, this is extremely practical. For instance, you can then easily emulate other languages (such as SQL) natively with the typesystem and get all the benefits

Btw, this is extremely practical. For instance, you can then easily emulate other languages (such as SQL) natively with the typesystem and get all the benefits of the compiler/IDE, rather than having to use a library with custom syntax or a raw SQL string and having syntax/semantic errors very late at runtime only. That alone is worth it imho.