For all primitive types except NullType and NothingType, this is specified by the IR spec in the sense that it is visible in the result of classOf[Array[Prim]].getName() (e.g., that is "[I" for Array[Int]).
For NullType and NothingType, the char codes are 'N' and 'E', respectively.
For all primitive types except NullType and NothingType, this is specified by the IR spec in the sense that it is the result of classOf[Prim].getName().
For NullType and NothingType, the names are "null" and "nothing", respectively.