[project @ 2002-03-14 15:27:15 by simonpj]

[ghc-hetmet.git] / ghc / compiler / basicTypes / Var.lhs

diff --git a/ghc/compiler/basicTypes/Var.lhs b/ghc/compiler/basicTypes/Var.lhs
index b9d7cf7..deff82a 100644 (file)
--- a/ghc/compiler/basicTypes/Var.lhs
+++ b/ghc/compiler/basicTypes/Var.lhs
@@ -14,20 +14,19 @@ module Var (
        tyVarName, tyVarKind,
        setTyVarName, setTyVarUnique,
        mkTyVar, mkSysTyVar, 
-       newMutTyVar, newSigTyVar,
-       readMutTyVar, writeMutTyVar, makeTyVarImmutable,
+       newMutTyVar, readMutTyVar, writeMutTyVar, makeTyVarImmutable, 
 
        -- Ids
        Id, DictId,
        idName, idType, idUnique, idInfo, modifyIdInfo, maybeModifyIdInfo,
        setIdName, setIdUnique, setIdInfo, lazySetIdInfo, 
-       setIdNoDiscard, zapSpecPragmaId,
+       setIdLocalExported, zapSpecPragmaId,
 
        globalIdDetails, setGlobalIdDetails, 
 
        mkLocalId, mkGlobalId, mkSpecPragmaId,
 
-       isTyVar, isMutTyVar, isSigTyVar,
+       isTyVar, isMutTyVar, mutTyVarDetails,
        isId, isLocalVar, isLocalId,
        isGlobalId, isExportedId, isSpecPragmaId,
        mustHaveLocalBinding
@@ -36,12 +35,13 @@ module Var (
 #include "HsVersions.h"
 
 import {-# SOURCE #-}  TypeRep( Type, Kind )
+import {-# SOURCE #-}  TcType( TyVarDetails )
 import {-# SOURCE #-}  IdInfo( GlobalIdDetails, notGlobalId,
                                IdInfo, seqIdInfo )
 
 import Name            ( Name, OccName, NamedThing(..),
                          setNameUnique, setNameOcc, nameUnique, 
-                         mkSysLocalName, isExternallyVisibleName
+                         mkSystemName
                        )
 import Unique          ( Unique, Uniquable(..), mkUniqueGrimily, getKey )
 import FastTypes
@@ -66,7 +66,7 @@ in its @VarDetails@.
 \begin{code}
 data Var
   = Var {
-       varName    :: Name,
+       varName    :: !Name,
        realUnique :: FastInt,          -- Key for fast comparison
                                        -- Identical to the Unique in the name,
                                        -- cached here for speed
@@ -77,15 +77,14 @@ data Var
 
 data VarDetails
   = LocalId            -- Used for locally-defined Ids (see NOTE below)
-       LocalIdDetails  -- True <=> exported; don't discard even if dead
+       LocalIdDetails
 
   | GlobalId           -- Used for imported Ids, dict selectors etc
        GlobalIdDetails
 
   | TyVar
   | MutTyVar (IORef (Maybe Type))      -- Used during unification;
-            Bool                       -- True <=> this is a type signature variable, which
-                                       --          should not be unified with a non-tyvar type
+            TyVarDetails
 
        -- For a long time I tried to keep mutable Vars statically type-distinct
        -- from immutable Vars, but I've finally given up.   It's just too painful.
@@ -104,6 +103,8 @@ LocalId and GlobalId
 A GlobalId is
   * always a constant (top-level)
   * imported, or data constructor, or primop, or record selector
+  * has a Unique that is globally unique across the whole
+    GHC invocation (a single invocation may compile multiple modules)
 
 A LocalId is 
   * bound within an expression (lambda, case, local let(rec))
@@ -194,26 +195,17 @@ mkSysTyVar uniq kind = Var { varName    = name
                           , varInfo    = pprPanic "mkSysTyVar" (ppr name)
                           }
                     where
-                      name = mkSysLocalName uniq SLIT("t")
-
-newMutTyVar :: Name -> Kind -> IO TyVar
-newMutTyVar name kind = newTyVar name kind False
-
-newSigTyVar :: Name -> Kind -> IO TyVar
--- 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)
-                 })
+                      name = mkSystemName uniq FSLIT("t")
+
+newMutTyVar :: Name -> Kind -> TyVarDetails -> IO TyVar
+newMutTyVar name kind details 
+  = do loc <- newIORef Nothing
+       return (Var { varName    = name
+                  , realUnique = getKey (nameUnique name)
+                  , varType    = kind
+                  , varDetails = MutTyVar loc details
+                  , varInfo    = pprPanic "newMutTyVar" (ppr name)
+                  })
 
 readMutTyVar :: TyVar -> IO (Maybe Type)
 readMutTyVar (Var {varDetails = MutTyVar loc _}) = readIORef loc
@@ -223,6 +215,9 @@ writeMutTyVar (Var {varDetails = MutTyVar loc _}) val = writeIORef loc val
 
 makeTyVarImmutable :: TyVar -> TyVar
 makeTyVarImmutable tyvar = tyvar { varDetails = TyVar}
+
+mutTyVarDetails :: TyVar -> TyVarDetails
+mutTyVarDetails (Var {varDetails = MutTyVar _ details}) = details
 \end{code}
 
 
@@ -251,10 +246,8 @@ setIdUnique = setVarUnique
 setIdName :: Id -> Name -> Id
 setIdName = setVarName
 
-setIdNoDiscard :: Id -> Id
-setIdNoDiscard id 
-  = WARN( not (isLocalId id), ppr id )
-    id { varDetails = LocalId Exported }
+setIdLocalExported :: Id -> Id
+setIdLocalExported id = id { varDetails = LocalId Exported }
 
 zapSpecPragmaId :: Id -> Id
 zapSpecPragmaId id 
@@ -308,7 +301,7 @@ mkGlobalId details name ty info = mkId name ty (GlobalId details) info
 \end{code}
 
 \begin{code}
-isTyVar, isMutTyVar, isSigTyVar                 :: Var -> Bool
+isTyVar, isMutTyVar                     :: Var -> Bool
 isId, isLocalVar, isLocalId                     :: Var -> Bool
 isGlobalId, isExportedId, isSpecPragmaId :: Var -> Bool
 mustHaveLocalBinding                    :: Var -> Bool
@@ -321,8 +314,6 @@ isTyVar var = case varDetails var of
 isMutTyVar (Var {varDetails = MutTyVar _ _}) = True
 isMutTyVar other                            = False
 
-isSigTyVar (Var {varDetails = MutTyVar _ is_sig}) = is_sig
-isSigTyVar other                                 = False
 
 isId var = case varDetails var of
                LocalId _  -> True