[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 simonpj):

 > Ah, it seems I have two make sure mkTypeableBinds is called before
 simplifyTop in tcRnSrcDecls.

 This is a stronger reason for deferring the desugaring of `Typeable`
 evidence: such evidence necessarily refers to top-level Haskell binding
 for the type representation of a type constructor defined in this module.
 e.g. To solve `Typeable T` we need to refer to `T`'s type representation.

 But we haven't generated those top-level bindings yet.

 In general, such evidence-solving may take place before `simplifyTop` is
 called; e.g. in `simplifyInfer`.

 Given this, better to defer to the desugarer I think, to postpone any
 evidence-solving that requires bindings that might be generated in this
 very module.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14691#comment:20>
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