+unpackPackageId :: PackageId -> Maybe PackageIdentifier
+unpackPackageId p
+ = case [ pid | (pid,"") <- readP_to_S parsePackageId str ] of
+ [] -> Nothing
+ (pid:_) -> Just pid
+ where str = packageIdString p
+
+-- -----------------------------------------------------------------------------
+-- Package Ids that are wired in
+
+-- Certain packages are "known" to the compiler, in that we know about certain
+-- entities that reside in these packages, and the compiler needs to
+-- declare static Modules and Names that refer to these packages. Hence
+-- the wired-in packages can't include version numbers, since we don't want
+-- to bake the version numbers of these packages into GHC.
+--
+-- So here's the plan. Wired-in packages are still versioned as
+-- normal in the packages database, and you can still have multiple
+-- versions of them installed. However, for each invocation of GHC,
+-- only a single instance of each wired-in package will be recognised
+-- (the desired one is selected via -package/-hide-package), and GHC
+-- will use the unversioned PackageId below when referring to it,
+-- including in .hi files and object file symbols. Unselected
+-- versions of wired-in packages will be ignored, as will any other
+-- package that depends directly or indirectly on it (much as if you
+-- had used -ignore-package).
+
+basePackageId = fsToPackageId FSLIT("base")
+rtsPackageId = fsToPackageId FSLIT("rts")
+haskell98PackageId = fsToPackageId FSLIT("haskell98")
+thPackageId = fsToPackageId FSLIT("template-haskell")
+
+-- This is the package Id for the program. It is the default package
+-- Id if you don't specify a package name. We don't add this prefix
+-- to symbol name, since there can be only one main package per program.
+mainPackageId = fsToPackageId FSLIT("main")