[GHC] #14691: Replace EvTerm with CoreExpr

[GHC]

#14691: Replace EvTerm with CoreExpr
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        Reporter:  nomeata           |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.3
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by nomeata):

 When moving this desugaring code into smart constructors that are run by
 the type checker, it need to be able ot use functions like
 `mkStringExprFS` which require `MonadThings`. But the type checker monad
 does not have a suitable instance:
 {{{
 No instance for (HscTypes.MonadThings TcS)
 }}}

 Is that by design, or has just nobody bothered so far to create such an
 instance?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14691#comment:4>
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