I have the same problem with a compiler plugin that I am writing. In GHC Core I need to get from a dict-fun identifier (e.g. $fMyClassDouble to the type class instance bindr (starting with $c). lookupInstEnv from the InstEnv module seemed to do it, but it seems to look up the matching key from a set of instEnv keys and not anything that contains the instance bindr. Not sure. Where is the dictionary lookup that gives me the bindr? What I did so far: evalExpr :: DynFlags -> ModGuts -> CoreExpr -> Var -> CoreM NodeType evalExpr dflags guts (Var iD) v = do hsc_env <- getHscEnv eps <- liftIO (hscEPS hsc_env) let instEnvs = InstEnvs (eps_inst_env eps) (mg_inst_env guts) (mkModuleSet (dep_orphs (mg_deps guts))) let ty = tyConAppTyCon_maybe (idType iD) let cl = fromJust (tyConClass_maybe (fromJust ty)) let tys = snd (splitTyConApp (idType iD)) let (matches,_,_) | isDictId iD = lookupInstEnv False instEnvs cl tys | otherwise = ([],[],[]) let inst = map (nameStableString . varName . is_dfun . fst) matches liftIO $ B.appendFile ("debug.txt") (B.pack (show inst))
| lookupInstEnv from the InstEnv module seemed to do it, but it seems to | look up the matching key from a set of instEnv keys and not anything | that contains the instance bindr. Not sure. I couldn't understand this. lookupInstEnv is probably what you want. It returns a ClsInstLookupResult type InstMatch = (ClsInst, [DFunInstType]) type ClsInstLookupResult = ( [InstMatch] -- Successful matches , [ClsInst] -- These don't match but do unify , [InstMatch] ) -- Unsafe overlapped instances under Safe Haskell -- (see Note [Safe Haskell Overlapping Instances] in -- TcSimplify). Inside the ClsInst of the InstMatches you'll find a DFunId, which is (I think) what you are after. Simon | -----Original Message----- | From: ghc-devs [mailto:ghc-devs-bounces@haskell.org] On Behalf Of | Tillmann Vogt via ghc-devs | Sent: 19 October 2017 18:13 | To: ghc-devs@haskell.org | Subject: Re: Determine instance method from class method callsite | | I have the same problem with a compiler plugin that I am writing. | | In GHC Core I need to get from a dict-fun identifier (e.g. | $fMyClassDouble to the type class instance bindr (starting with $c). | | lookupInstEnv from the InstEnv module seemed to do it, but it seems to | look up the matching key from a set of instEnv keys and not anything | that contains the instance bindr. Not sure. | | Where is the dictionary lookup that gives me the bindr? | | What I did so far: | | evalExpr :: DynFlags -> ModGuts -> CoreExpr -> Var -> CoreM NodeType | evalExpr dflags guts (Var iD) v = do | | hsc_env <- getHscEnv | eps <- liftIO (hscEPS hsc_env) | let instEnvs = InstEnvs (eps_inst_env eps) | (mg_inst_env guts) | (mkModuleSet (dep_orphs (mg_deps guts))) | let ty = tyConAppTyCon_maybe (idType iD) | let cl = fromJust (tyConClass_maybe (fromJust ty)) | let tys = snd (splitTyConApp (idType iD)) | let (matches,_,_) | isDictId iD = lookupInstEnv False instEnvs cl | tys | | otherwise = ([],[],[]) | | let inst = map (nameStableString . varName . is_dfun . fst) matches | | liftIO $ B.appendFile ("debug.txt") (B.pack (show inst)) | _______________________________________________ | ghc-devs mailing list | ghc-devs@haskell.org | https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmail.h | askell.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fghc- | devs&data=02%7C01%7Csimonpj%40microsoft.com%7Caa82860ef55a428ab1e908d5 | 1714eb63%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C6364403011206865 | 53&sdata=lpbVMttf5W7p%2FGIs3e5pTd6ZS0w4i%2BHwUr9ysRnuCBE%3D&reserved=0
participants (2)
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Simon Peyton Jones -
Tillmann Vogt