+import Class ( FunDep )
+import TysWiredIn ( tupleTyCon, listTyCon, parrTyCon, charTyCon )
+import Name ( Name, getName, isTyVarName )
+import NameSet
+import BasicTypes ( Boxity )
+import SrcLoc ( Located(..), unLoc )
+\end{code}
+
+%************************************************************************
+%* *
+\subsection{Free variables}
+%* *
+%************************************************************************
+
+These free-variable finders returns tycons and classes too.
+
+\begin{code}
+charTyCon_name, listTyCon_name, parrTyCon_name :: Name
+charTyCon_name = getName charTyCon
+listTyCon_name = getName listTyCon
+parrTyCon_name = getName parrTyCon
+
+tupleTyCon_name :: Boxity -> Int -> Name
+tupleTyCon_name boxity n = getName (tupleTyCon boxity n)
+
+extractHsTyVars :: LHsType Name -> NameSet
+extractHsTyVars x = filterNameSet isTyVarName (extractHsTyNames x)
+
+extractFunDepNames :: FunDep Name -> NameSet
+extractFunDepNames (ns1, ns2) = mkNameSet ns1 `unionNameSets` mkNameSet ns2
+
+extractHsTyNames :: LHsType Name -> NameSet
+extractHsTyNames ty
+ = getl ty
+ where
+ getl (L _ ty) = get ty
+
+ get (HsAppTy ty1 ty2) = getl ty1 `unionNameSets` getl ty2
+ get (HsListTy ty) = unitNameSet listTyCon_name `unionNameSets` getl ty
+ get (HsPArrTy ty) = unitNameSet parrTyCon_name `unionNameSets` getl ty
+ get (HsTupleTy con tys) = extractHsTyNames_s tys
+ get (HsFunTy ty1 ty2) = getl ty1 `unionNameSets` getl ty2
+ get (HsPredTy p) = extractHsPredTyNames (unLoc p)
+ get (HsOpTy ty1 op ty2) = getl ty1 `unionNameSets` getl ty2 `unionNameSets` unitNameSet (unLoc op)
+ get (HsParTy ty) = getl ty
+ get (HsNumTy n) = emptyNameSet
+ get (HsTyVar tv) = unitNameSet tv
+ get (HsSpliceTy _) = emptyNameSet -- Type splices mention no type variables
+ get (HsKindSig ty k) = getl ty
+ get (HsForAllTy _ tvs
+ ctxt ty) = (extractHsCtxtTyNames ctxt
+ `unionNameSets` getl ty)
+ `minusNameSet`
+ mkNameSet (hsLTyVarNames tvs)
+
+extractHsTyNames_s :: [LHsType Name] -> NameSet
+extractHsTyNames_s tys = foldr (unionNameSets . extractHsTyNames) emptyNameSet tys
+
+extractHsCtxtTyNames :: LHsContext Name -> NameSet
+extractHsCtxtTyNames (L _ ctxt)
+ = foldr (unionNameSets . extractHsPredTyNames . unLoc) emptyNameSet ctxt
+
+-- You don't import or export implicit parameters,
+-- so don't mention the IP names
+extractHsPredTyNames (HsClassP cls tys)
+ = unitNameSet cls `unionNameSets` extractHsTyNames_s tys
+extractHsPredTyNames (HsIParam n ty)
+ = extractHsTyNames ty