-s%
+%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section{@Vars@: Variables}
setNameUnique, setNameOcc, nameUnique,
mkSysLocalName, isExternallyVisibleName
)
-import BasicTypes ( Unused )
+import FastTypes
import Outputable
import IOExts ( IORef, newIORef, readIORef, writeIORef )
\end{code}
-
%************************************************************************
%* *
\subsection{The main data type declarations}
data Var
= Var {
varName :: Name,
- realUnique :: Int#, -- Key for fast comparison
+ realUnique :: FastInt, -- Key for fast comparison
-- Identical to the Unique in the name,
-- cached here for speed
varType :: Type,
name = mkSysLocalName uniq SLIT("t")
newMutTyVar :: Name -> Kind -> IO TyVar
-newMutTyVar name kind =
- do loc <- newIORef Nothing
- return (Var { varName = name
- , realUnique = getKey (nameUnique name)
- , varType = kind
- , varDetails = MutTyVar loc False
- , varInfo = pprPanic "newMutTyVar" (ppr name)
- })
+newMutTyVar name kind = newTyVar name kind False
newSigTyVar :: Name -> Kind -> IO TyVar
-newSigTyVar name kind =
- do loc <- newIORef Nothing
- return (Var { varName = name
- , realUnique = getKey (nameUnique name)
- , varType = kind
- , varDetails = MutTyVar loc True
- , varInfo = pprPanic "newSigTyVar" (ppr name)
- })
+-- Type variables from type signatures are still mutable, because
+-- they may get unified with type variables from other signatures
+-- But they do contain a flag to distinguish them, so we can tell if
+-- we unify them with a non-type-variable.
+newSigTyVar name kind = newTyVar name kind True
+
+newTyVar name kind is_sig
+ = do loc <- newIORef Nothing
+ return (Var { varName = name
+ , realUnique = getKey (nameUnique name)
+ , varType = kind
+ , varDetails = MutTyVar loc is_sig
+ , varInfo = pprPanic "newMutTyVar" (ppr name)
+ })
readMutTyVar :: TyVar -> IO (Maybe Type)
readMutTyVar (Var {varDetails = MutTyVar loc _}) = readIORef loc