Simplify conversion of top level bindings to DAML-LF (#2730)

At the top level we don't care if bindings are recursive or not. The logic
that takes care of this ignorance is currently mixed with the actual logic
for converting the bindings.

This PR separates these concerns properly. This is also in preparation for
another upcoming change which needs access to all top level bindings.

compiler/damlc/daml-lf-conversion/src/DA/Daml/LFConversion.hs

@@ -235,7 +235,7 @@ convertRational env num denom
 
 convertModule :: LF.Version -> MS.Map UnitId T.Text -> NormalizedFilePath -> CoreModule -> Either FileDiagnostic LF.Module
 convertModule lfVersion pkgMap file x = runConvertM (ConversionEnv file Nothing) $ do
-    definitions <- concatMapM (convertBind env) $ filter (not . isTypeableInfo) $ cm_binds x
+    definitions <- concatMapM (convertBind env) binds
     types <- concatMapM (convertTypeDef env) (eltsUFM (cm_types x))
     pure (LF.moduleFromDefinitions lfModName (Just $ fromNormalizedFilePath file) flags (types ++ definitions))
     where
@@ -243,6 +243,16 @@ convertModule lfVersion pkgMap file x = runConvertM (ConversionEnv file Nothing)
         thisUnitId = GHC.moduleUnitId $ cm_module x
         lfModName = convertModuleName ghcModName
         flags = LF.daml12FeatureFlags
+        binds =
+          [ bind
+          | bindGroup <- cm_binds x
+          , bind <- case bindGroup of
+              NonRec name body
+                -- NOTE(MH): We can't cope with the generated Typeable stuff, so remove those bindings
+                | any (`T.isPrefixOf` getOccText name) ["$krep", "$tc", "$trModule"] -> []
+                | otherwise -> [(name, body)]
+              Rec binds -> binds
+          ]
         newtypes =
           [ (wrappedT, (t, mkUnbranchedAxInstCo Representational co [] []))
           | ATyCon t <- eltsUFM (cm_types x)
@@ -258,11 +268,6 @@ convertModule lfVersion pkgMap file x = runConvertM (ConversionEnv file Nothing)
           , envNewtypes = newtypes
           }
 
--- | We can't cope with the generated Typeable stuff, so remove those bindings
-isTypeableInfo :: Bind Var -> Bool
-isTypeableInfo (NonRec name _) = any (`T.isPrefixOf` getOccText name) ["$krep", "$tc", "$trModule"]
-isTypeableInfo _ = False
-
 -- TODO(MH): We should run this on an `LF.Expr` instead of a `GHC.Expr`.
 -- This will avoid a fair bit of repetition.
 convertGenericTemplate :: Env -> GHC.Expr Var -> ConvertM (Template, LF.Expr)
@@ -452,8 +457,8 @@ convertCtors env (Ctors name _ tys cs) = do
               mkETyLams tys $ mkETmLams (zipExact (map fieldToVar fldNames') fldTys) $ EVariantCon tcon ctorName ctorArg
 
 
-convertBind :: Env -> CoreBind -> ConvertM [Definition]
-convertBind env (NonRec name x)
+convertBind :: Env -> (Var, GHC.Expr Var) -> ConvertM [Definition]
+convertBind env (name, x)
     | DFunId _ <- idDetails name
     , TypeCon (Is tplInst) _ <- varType name
     , "Instance" `T.isSuffixOf` fsToText tplInst
@@ -461,10 +466,6 @@ convertBind env (NonRec name x)
         (tmpl, dict) <- convertGenericTemplate env x
         name' <- convValWithType env name
         pure [DTemplate tmpl, defValue name name' dict]
-convertBind env x = convertBind2 env x
-
-convertBind2 :: Env -> CoreBind -> ConvertM [Definition]
-convertBind2 env (NonRec name x)
     | Just internals <- lookupUFM internalFunctions (envGHCModuleName env)
     , getOccFS name `elementOfUniqSet` internals
     = pure []
@@ -493,7 +494,7 @@ convertBind2 env (NonRec name x)
     -- This workaround should be removed once we either have a proper lambda
     -- lifter or DAML-LF supports local recursion.
     | (as, Let (Rec [(f, Lam v y)]) (Var f')) <- collectBinders x, f == f'
-    = convertBind2 env $ NonRec name $ mkLams as $ Lam v $ Let (NonRec f $ mkVarApps (Var name) as) y
+    = convertBind env $ (,) name $ mkLams as $ Lam v $ Let (NonRec f $ mkVarApps (Var name) as) y
     | otherwise
     = withRange (convNameLoc name) $ do
     x' <- convertExpr env x
@@ -506,7 +507,6 @@ convertBind2 env (NonRec name x)
           _ -> id
     name' <- convValWithType env name
     pure [defValue name name' (sanitize x')]
-convertBind2 env (Rec xs) = concatMapM (\(a, b) -> convertBind env (NonRec a b)) xs
 
 -- NOTE(MH): These are the names of the builtin DAML-LF types whose Surface
 -- DAML counterpart is not defined in 'GHC.Types'. They are all defined in