Re: lookupRdrNameInModuleForPlugins with constructors

I'm now able to look up value identifiers, type constructors (including classes), and regular data constructors, but not dictionary constructors. Here's my failing effort to look up a dictionary constructor (in CoreM): hasRepThing <- maybe (panic "HasRep lookup failure") lookupThing =<< (liftIO $ lookupRdrNameInModuleForPlugins hsc_env (mkModuleName "Circat.Rep") (Unqual (mkDataOcc "C:HasRep"))) pprTrace "mkReifyEnv HasRep thing:" (ppr hasRepThing) (return ()) Result: ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.1.20160307 for x86_64-apple-darwin): HasRep lookup failure Same failure when I use the name string "HasRep" in place of "C:HasRep". Any idea what I'm doing wrong here? -- Conal On Tue, Mar 22, 2016 at 5:40 PM, Conal Elliott wrote:

Got it. Silly me. Thanks!! - Conal

On Tue, Mar 22, 2016 at 5:25 PM, Andrew Farmer wrote:

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Er, dictionary... sorry, mkDataOccFS

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mkVarUnqual calls mkVarOccFS, which constructs an OccName in the varName namespace. You need to construct your RdrName via mkTyVarOcc, which picks the Type/Class namespace.

On Tue, Mar 22, 2016 at 5:09 PM, Conal Elliott wrote:

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I'm trying to construct a dictionary in a GHC plugin. I'm stuck on finding the constructor for the dictionary. When I use `-ddump-simpl` on the module that defines the class, I see "Circat.Rep.C:HasRep". To try finding

On Tue, Mar 22, 2016 at 5:24 PM, Andrew Farmer wrote: that

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constructor, I say

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lookupRdrNameInModuleForPlugins hsc_env (mkModuleName "Circat.Rep") (mkVarUnqual "C:HasRep")

However, I keep getting `Nothing` as a result. (Same without the "C:".) I've also had this same difficulty when looking up constructors for algebraic data types and when looking up TyCons. For regular value Ids, lookup succeeds.

What am I missing?

Thanks, - Conal

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