isImmutableTyVar, isSkolemTyVar, isMetaTyVar, isMetaTyVarTy,
isSigTyVar, isExistentialTyVar, isTyConableTyVar,
metaTvRef,
- isFlexi, isIndirect, isRuntimeUnk, isUnk,
+ isFlexi, isIndirect, isUnkSkol, isRuntimeUnkSkol,
--------------------------------
-- Builders
-- 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,
-- The Name is the name of the function from whose
-- type signature we got this skolem
+ | TcsTv -- A MetaTv allocated by the constraint solver
+ -- Its particular property is that it is always "touchable"
+ -- Nevertheless, the constraint solver has to try to guess
+ -- what type to instantiate it to
+
----------------------------------
-- SkolemInfo describes a site where
-- a) type variables are skolemised
| 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)
pprTcTyVarDetails (SkolemTv _) = ptext (sLit "sk")
pprTcTyVarDetails (FlatSkol {}) = ptext (sLit "fsk")
pprTcTyVarDetails (MetaTv TauTv _) = ptext (sLit "tau")
+pprTcTyVarDetails (MetaTv TcsTv _) = ptext (sLit "tcs")
pprTcTyVarDetails (MetaTv (SigTv _) _) = ptext (sLit "sig")
pprUserTypeCtxt :: UserTypeCtxt -> SDoc
where
ppr_details (SkolemTv info) = ppr_skol info
ppr_details (FlatSkol {}) = ptext (sLit "is a flattening type variable")
- ppr_details (MetaTv TauTv _) = ptext (sLit "is a meta type variable")
- ppr_details (MetaTv (SigTv n) _) = ptext (sLit "is bound by the type signature for") <+> quotes (ppr n)
+ ppr_details (MetaTv (SigTv n) _) = ptext (sLit "is bound by the type signature for")
+ <+> quotes (ppr n)
+ ppr_details (MetaTv _ _) = ptext (sLit "is a meta type variable")
ppr_skol UnkSkol = ptext (sLit "is an unknown type variable") -- Unhelpful
ppr_skol RuntimeUnkSkol = ptext (sLit "is an unknown runtime type")
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
-- not a SigTv
= ASSERT( isTcTyVar tv)
case tcTyVarDetails tv of
- MetaTv TauTv _ -> True
- _ -> False
+ MetaTv (SigTv _) _ -> False
+ _ -> True
isSkolemTyVar tv
= ASSERT2( isTcTyVar tv, ppr tv )
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}
mkDictTy :: Class -> [Type] -> Type
mkDictTy clas tys = mkPredTy (ClassP clas tys)
-
-
isDictLikeTy :: Type -> Bool
-- Note [Dictionary-like types]
isDictLikeTy ty | Just ty' <- tcView ty = isDictTy ty'