[GHC] #14391: Make the simplifier independent of the typechecker

[GHC]

#14391: Make the simplifier independent of the typechecker
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        Reporter:  nomeata           |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.3
      Resolution:                    |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4503
       Wiki Page:                    |
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Comment (by monoidal):

 Regarding update (April 2018) from the ticket description:

 Point 1: I agree that we can move `thNameToGhcName` to GhcPlugins; it's
 not used anywhere. Optionally, we could also move there `ioLookupDataCon`
 and `ioLookupDataCon_maybe` (they are also unused). Either way, it's
 cheap.

 Point 2: I understand the goal is to move `lookupGlobal` away from
 typecheck/ directory. Currently `lookupGlobal` calls `lookupGlobal_maybe`,
 which calls `lookupImported_maybe`, which calls `importDecl_maybe`, which
 calls `initIfaceLoad`, which is in TcRnMonad. So I see that we can weaken
 the dependency of CoreMonad from TcEnv to TcRnMonad, but I don't see yet
 how to get rid of it completely. Is my understanding correct?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14391#comment:30>
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