[GHC] #12895: Lookup rules associated with functions/values in GHCI

[GHC]

#12895: Lookup rules associated with functions/values in GHCI
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        Reporter:  harpocrates       |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  GHCi              |              Version:  8.0.1
      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 harpocrates):

 Replying to [comment:1 simonpj]:
 > I can see the value, and I don't think it'd be hard.  Happy to advise.
 >
 > First look at how `:info` works, I suggest.
 >
 > Simon

 After a quick survey of how `:info` works, I think I'm starting to see
 what needs to be done (or getting lost). As `:info` does for finding
 instances, I'll need to start by loading some interfaces to make sure I
 really do find all my `RULES`, then I should be able to get out of the
 `ExternalPackageState` a `RuleBase`, at which point I just need to filter
 for the right `CoreRule`s .

 However, is `CoreRule` really the abstraction I'm looking for? I noticed
 there is also an interface level `IfaceRule` and a type checker level
 `LRuleDecl Id` (from `TcGblEnv`) so I thought I'd ask...

 More generally, how little of this sounds right? :)

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12895#comment:2>
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