+initTcEnv :: HomeSymbolTable -> PackageTypeEnv -> IO TcEnv
+initTcEnv hst pte
+ = do { gtv_var <- newIORef emptyVarSet ;
+ return (TcEnv { tcGST = lookup,
+ tcGEnv = emptyNameEnv,
+ tcInsts = emptyInstEnv,
+ tcLEnv = emptyNameEnv,
+ tcTyVars = gtv_var
+ })}
+ where
+ lookup name | isInternalName name = Nothing
+ | otherwise = lookupType hst pte name
+
+
+tcEnvClasses env = typeEnvClasses (tcGEnv env)
+tcEnvTyCons env = typeEnvTyCons (tcGEnv env)
+tcEnvIds env = typeEnvIds (tcGEnv env)
+tcLEnvElts env = nameEnvElts (tcLEnv env)
+
+getTcGEnv (TcEnv { tcGEnv = genv }) = genv
+
+tcInLocalScope :: TcEnv -> Name -> Bool
+tcInLocalScope env v = v `elemNameEnv` (tcLEnv env)
+\end{code}
+
+\begin{code}
+data TcTyThing
+ = AGlobal TyThing -- Used only in the return type of a lookup
+ | ATcId TcId -- Ids defined in this module
+ | ATyVar TyVar -- Type variables
+ | AThing TcKind -- Used temporarily, during kind checking
+-- Here's an example of how the AThing guy is used
+-- Suppose we are checking (forall a. T a Int):
+-- 1. We first bind (a -> AThink kv), where kv is a kind variable.
+-- 2. Then we kind-check the (T a Int) part.
+-- 3. Then we zonk the kind variable.
+-- 4. Now we know the kind for 'a', and we add (a -> ATyVar a::K) to the environment
+
+\end{code}
+
+This data type is used to help tie the knot
+ when type checking type and class declarations
+
+\begin{code}
+data TyThingDetails = SynTyDetails Type
+ | DataTyDetails ThetaType (DataConDetails DataCon) [Id]
+ | ClassDetails ThetaType [Id] [ClassOpItem] DataCon
+ | ForeignTyDetails -- Nothing yet
+\end{code}
+
+%************************************************************************
+%* *
+\subsection{Basic lookups}
+%* *
+%************************************************************************
+
+\begin{code}
+lookup_global :: TcEnv -> Name -> Maybe TyThing
+ -- Try the global envt and then the global symbol table
+lookup_global env name
+ = case lookupNameEnv (tcGEnv env) name of
+ Just thing -> Just thing
+ Nothing -> tcGST env name
+
+lookup_local :: TcEnv -> Name -> Maybe TcTyThing
+ -- Try the local envt and then try the global
+lookup_local env name
+ = case lookupNameEnv (tcLEnv env) name of
+ Just thing -> Just thing
+ Nothing -> case lookup_global env name of
+ Just thing -> Just (AGlobal thing)
+ Nothing -> Nothing
+\end{code}
+
+\begin{code}
+type RecTcEnv = TcEnv
+-- This environment is used for getting the 'right' IdInfo
+-- on imported things and for looking up Ids in unfoldings
+-- The environment doesn't have any local Ids in it
+
+tcLookupRecId_maybe :: RecTcEnv -> Name -> Maybe Id
+tcLookupRecId_maybe env name = case lookup_global env name of
+ Just (AnId id) -> Just id
+ other -> Nothing
+
+tcLookupRecId :: RecTcEnv -> Name -> Id
+tcLookupRecId env name = case lookup_global env name of
+ Just (AnId id) -> id
+ Nothing -> pprPanic "tcLookupRecId" (ppr name)