Why can't we re-install the template-haskell package?

[Richard Eisenberg]

I have to admit I don't have a strong grasp on what "reinstallable" implies. Does a package get the same hash after reinstalling? What could make a package not reinstallable? Why aren't packages reinstallable today? Why isn't ghc-prim reinstallable?

My concern stems from the fact that ghc is interlinked with TH in at least two ways:
 - GHC imports definitions from template-haskell. But this is the same as the way GHC is involved with, say, `base`.
 - GHC also wires in some template-haskell definitions. This is the aspect I am worried about. Is `base` reinstallable? If so, then perhaps template-haskell could be, too.

Thanks,
Richard