[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 simonpj):

 Re lookupGlobal, there is a reason for this!  If you look up `Complex`,
 say, then GHC might need to read in `Complex.hi`, and deserialise and
 typecheck it (`TcIface` does this).  The "typechecking" will never fail,
 unless it's a stale `.hi` file or something, but it's the process of
 turning a bare syntax tree into `TyCons`, `Ids` etc.

 Now that does not need the full glory of the `Tc` monad; but it does need
 quite a bit.  Teasing out exactly what it uses, and perhaps making a
 stripped-down `Tc` monad just for that, might be worthwhile.  But it would
 be work, perhaps more than is justified until we have a stronger cause.

 I'm sure there are lots of other ways in which things could be better
 structured too.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14391#comment:33>
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