Are there fully-qualified type paths to the primitive types like `u8` ?

Something I noticed just now: (It seems) there are no ways to explicitly point the built-in primitive types in the rust code isn't it? Neither ::std::u8 or ::core::u8 are not the primitive types but the module names.

The reference says these types are "Language preludes", but there are no descriptions about where those types are actually defined in.

Is there any way to do this?