A (final) re-engineering of the new typechecker

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

diff --git a/compiler/typecheck/TcType.lhs b/compiler/typecheck/TcType.lhs
index b20d32e..8a95b0f 100644 (file)
--- a/compiler/typecheck/TcType.lhs
+++ b/compiler/typecheck/TcType.lhs
@@ -30,7 +30,7 @@ module TcType (
   isImmutableTyVar, isSkolemTyVar, isMetaTyVar,  isMetaTyVarTy,
   isSigTyVar, isExistentialTyVar,  isTyConableTyVar,
   metaTvRef, 
-  isFlexi, isIndirect, isRuntimeUnk, isUnk,
+  isFlexi, isIndirect, isUnkSkol, isRuntimeUnkSkol,
 
   --------------------------------
   -- Builders
@@ -123,7 +123,8 @@ module TcType (
   -- Type substitutions
   TvSubst(..),         -- Representation visible to a few friends
   TvSubstEnv, emptyTvSubst, substEqSpec,
-  mkOpenTvSubst, zipOpenTvSubst, zipTopTvSubst, mkTopTvSubst, notElemTvSubst,
+  mkOpenTvSubst, zipOpenTvSubst, zipTopTvSubst, 
+  mkTopTvSubst, notElemTvSubst, unionTvSubst,
   getTvSubstEnv, setTvSubstEnv, getTvInScope, extendTvInScope, lookupTyVar,
   extendTvSubst, extendTvSubstList, isInScope, mkTvSubst, zipTyEnv,
   substTy, substTys, substTyWith, substTheta, substTyVar, substTyVars, substTyVarBndr,
@@ -334,6 +335,7 @@ data SkolemInfo
 
   | RuleSkol RuleName  -- The LHS of a RULE
   | GenSkol TcType     -- Bound when doing a subsumption check for ty
+
   | RuntimeUnkSkol      -- a type variable used to represent an unknown
                         -- runtime type (used in the GHCi debugger)
 
@@ -449,6 +451,9 @@ pprSkolTvBinding tv
                                   sep [pprSkolInfo info, 
                                        nest 2 (ptext (sLit "at") <+> ppr (getSrcLoc tv))]]
  
+instance Outputable SkolemInfo where
+  ppr = pprSkolInfo
+
 pprSkolInfo :: SkolemInfo -> SDoc
 -- Complete the sentence "is a rigid type variable bound by..."
 pprSkolInfo (SigSkol ctxt)  = pprUserTypeCtxt ctxt
@@ -669,15 +674,17 @@ isFlexi _     = False
 isIndirect (Indirect _) = True
 isIndirect _            = False
 
-isRuntimeUnk :: TyVar -> Bool
-isRuntimeUnk x | isTcTyVar x
-               , SkolemTv RuntimeUnkSkol <- tcTyVarDetails x = True
-               | otherwise = False
-
-isUnk :: TyVar -> Bool
-isUnk x | isTcTyVar x
-        , SkolemTv UnkSkol <- tcTyVarDetails x = True
-        | otherwise = False
+isRuntimeUnkSkol :: TyVar -> Bool
+-- Called only in TcErrors; see Note [Runtime skolems] there
+isRuntimeUnkSkol x | isTcTyVar x
+                  , SkolemTv RuntimeUnkSkol <- tcTyVarDetails x 
+                  = True
+                  | otherwise = False
+
+isUnkSkol :: TyVar -> Bool
+isUnkSkol x | isTcTyVar x
+            , SkolemTv UnkSkol <- tcTyVarDetails x = True
+            | otherwise = False
 \end{code}