Tidy-up sweep, following the Great Skolemisation Simplification

[ghc-hetmet.git] / compiler / typecheck / TcRnTypes.lhs

diff --git a/compiler/typecheck/TcRnTypes.lhs b/compiler/typecheck/TcRnTypes.lhs
index 7357669..4abb408 100644 (file)
--- a/compiler/typecheck/TcRnTypes.lhs
+++ b/compiler/typecheck/TcRnTypes.lhs
@@ -28,7 +28,7 @@ module TcRnTypes(
        ArrowCtxt(NoArrowCtxt), newArrowScope, escapeArrowScope,
 
        -- Constraints
-        Untouchables,
+        Untouchables(..), inTouchableRange, isNoUntouchables,
        WantedConstraints, emptyWanteds, andWanteds, extendWanteds,
        WantedConstraint(..), WantedEvVar(..), wantedEvVarLoc, 
         wantedEvVarToVar, wantedEvVarPred, splitWanteds,
@@ -68,11 +68,12 @@ import NameSet
 import Var
 import VarEnv
 import Module
-import UniqFM
 import SrcLoc
 import VarSet
 import ErrUtils
+import UniqFM
 import UniqSupply
+import Unique
 import BasicTypes
 import Bag
 import Outputable
@@ -256,6 +257,8 @@ data TcGblEnv
 
         tcg_ev_binds  :: Bag EvBind,       -- Top-level evidence bindings
        tcg_binds     :: LHsBinds Id,       -- Value bindings in this module
+        tcg_sigs      :: NameSet,          -- ...Top-level names that *lack* a signature
+        tcg_imp_specs :: [LTcSpecPrag],     -- ...SPECIALISE prags for imported Ids
        tcg_warns     :: Warnings,          -- ...Warnings and deprecations
        tcg_anns      :: [Annotation],      -- ...Annotations
        tcg_insts     :: [Instance],        -- ...Instances
@@ -381,7 +384,13 @@ data TcLclEnv              -- Changes as we move inside an expression
                         -- Why mutable? see notes with tcGetGlobalTyVars
 
        tcl_lie   :: TcRef WantedConstraints,    -- Place to accumulate type constraints
-       tcl_untch :: Untouchables                -- Untouchables
+
+       -- TcMetaTyVars have 
+       tcl_meta  :: TcRef Unique,  -- The next free unique for TcMetaTyVars
+                                   -- Guaranteed to be allocated linearly
+       tcl_untch :: Unique         -- Any TcMetaTyVar with 
+                                   --     unique >= tcl_untch is touchable
+                                   --     unique <  tcl_untch is untouchable
     }
 
 type TcTypeEnv = NameEnv TcTyThing
@@ -676,7 +685,29 @@ instance Outputable WhereFrom where
 v%************************************************************************
 
 \begin{code}
-type Untouchables = TcTyVarSet -- All MetaTyVars
+data Untouchables = NoUntouchables
+                  | TouchableRange
+                          Unique  -- Low end
+                          Unique  -- High end
+ -- A TcMetaTyvar is *touchable* iff its unique u satisfies
+ --   u >= low
+ --   u < high
+
+instance Outputable Untouchables where
+  ppr NoUntouchables = ptext (sLit "No untouchables")
+  ppr (TouchableRange low high) = ptext (sLit "Touchable range:") <+> 
+                                  ppr low <+> char '-' <+> ppr high
+
+isNoUntouchables :: Untouchables -> Bool
+isNoUntouchables NoUntouchables      = True
+isNoUntouchables (TouchableRange {}) = False
+
+inTouchableRange :: Untouchables -> TcTyVar -> Bool
+inTouchableRange NoUntouchables _ = True
+inTouchableRange (TouchableRange low high) tv 
+  = uniq >= low && uniq < high
+  where
+    uniq = varUnique tv
 
 type WantedConstraints = Bag WantedConstraint
 
@@ -702,11 +733,11 @@ type GivenLoc  = CtLoc SkolemInfo
 
 data Implication
   = Implic {  
-      ic_env_tvs :: Untouchables, -- Untouchables: unification variables
+      ic_untch :: Untouchables, -- Untouchables: unification variables
                                   -- free in the environment
-      ic_env     :: TcTypeEnv,    -- The type environment
+      ic_env   :: TcTypeEnv,    -- The type environment
                                  -- Used only when generating error messages
-         -- Generally, ic_env_tvs = tvsof(ic_env)
+         -- Generally, ic_untch is a superset of tvsof(ic_env)
          -- However, we don't zonk ic_env when zonking the Implication
          -- Instead we do that when generating a skolem-escape error message
 
@@ -812,10 +843,10 @@ pprWantedEvVarWithLoc (WantedEvVar v loc) = hang (pprEvVarWithType v)
 pprWantedEvVar        (WantedEvVar v _)   = pprEvVarWithType v
 
 instance Outputable Implication where
-  ppr (Implic { ic_env_tvs = env_tvs, ic_skols = skols, ic_given = given
+  ppr (Implic { ic_untch = untch, ic_skols = skols, ic_given = given
               , ic_wanted = wanted, ic_binds = binds, ic_loc = loc })
    = ptext (sLit "Implic") <+> braces 
-     (sep [ ptext (sLit "Untouchables = ") <+> ppr env_tvs
+     (sep [ ptext (sLit "Untouchables = ") <+> ppr untch
           , ptext (sLit "Skolems = ") <+> ppr skols
           , ptext (sLit "Given = ") <+> pprEvVars given
           , ptext (sLit "Wanted = ") <+> ppr wanted
@@ -848,13 +879,12 @@ ctLocOrigin (CtLoc o _ _) = o
 setCtLocOrigin :: CtLoc o -> o' -> CtLoc o'
 setCtLocOrigin (CtLoc _ s c) o = CtLoc o s c
 
-pprArising :: CtLoc CtOrigin -> SDoc
-pprArising loc = case ctLocOrigin loc of
-                   TypeEqOrigin -> empty
-                   _ -> text "arising from" <+> ppr (ctLocOrigin loc)
+pprArising :: CtOrigin -> SDoc
+pprArising (TypeEqOrigin {}) = empty
+pprArising orig              = text "arising from" <+> ppr orig
 
 pprArisingAt :: CtLoc CtOrigin -> SDoc
-pprArisingAt loc = sep [pprArising loc, text "at" <+> ppr (ctLocSpan loc)]
+pprArisingAt (CtLoc o s _) = sep [pprArising o, text "at" <+> ppr s]
 
 -------------------------------------------
 -- CtOrigin gives the origin of *wanted* constraints
@@ -864,7 +894,7 @@ data CtOrigin
 
   | SpecPragOrigin Name                -- Specialisation pragma for identifier
 
-  | TypeEqOrigin
+  | TypeEqOrigin EqOrigin
 
   | IPOccOrigin  (IPName Name) -- Occurrence of an implicit parameter
 
@@ -919,7 +949,7 @@ pprO StandAloneDerivOrigin = ptext (sLit "a 'deriving' declaration")
 pprO DefaultOrigin        = ptext (sLit "a 'default' declaration")
 pprO DoOrigin             = ptext (sLit "a do statement")
 pprO ProcOrigin                   = ptext (sLit "a proc expression")
-pprO TypeEqOrigin          = ptext (sLit "an equality")
+pprO (TypeEqOrigin eq)     = ptext (sLit "an equality") <+> ppr eq
 pprO AnnOrigin             = ptext (sLit "an annotation")
 
 instance Outputable EqOrigin where