Wired-in and known-key things

There are two categories of entities (Classes, TyCons, Ids) that GHC "knows about"; that is, information about them is baked into GHC's source code.

• A Wired-in thing is fully known to GHC.

• A known-key thing has a fixed, pre-allocated Unique or key. They should really be called "known-Name" things, because the baked-in knowledge is:
  • Its defining Module
  • Its OccName
  • Its Unique Almost all known-key names are defined in compiler/prelude/PrelNames; for example: PrelNames.eqClassName :: Name.

• An Orig RdrName? thing has a top-level definition of a RdrName, using the Orig constructor. Here, the baked-in information is:
  • Its defining Module
  • Its OccName Again, almost all of these are in compiler/prelude/PrelNames. Example: PrelNames.not_RDR :: RdrName.