+tcInstType :: TcType -> TcM ([TcTyVar], TcThetaType, TcType)
+-- tcInstType instantiates the outer-level for-alls of a TcType with
+-- fresh (mutable) type variables, splits off the dictionary part,
+-- and returns the pieces.
+tcInstType ty = tc_inst_type (mappM tcInstTyVar) ty
+
+
+---------------------------------------------
+tcInstSigType :: Name -> [Name] -> TcType -> TcM ([TcTyVar], TcThetaType, TcType)
+-- Instantiate a type with fresh SigSkol variables
+-- See Note [Signature skolems] in TcType.
+--
+-- Tne new type variables have the sane Name as the original *iff* they are scoped.
+-- For scoped tyvars, we don't need a fresh unique, because the renamer has made them
+-- unique, and it's better not to do so because we extend the envt
+-- with them as scoped type variables, and we'd like to avoid spurious
+-- 's = s' bindings in error messages
+--
+-- For non-scoped ones, we *must* instantiate fresh ones:
+--
+-- type T = forall a. [a] -> [a]
+-- f :: T;
+-- f = g where { g :: T; g = <rhs> }
+--
+-- We must not use the same 'a' from the defn of T at both places!!
+
+tcInstSigType id_name scoped_names ty = tc_inst_type (tcInstSigTyVars id_name scoped_names) ty
+
+tcInstSigTyVars :: Name -> [Name] -> [TyVar] -> TcM [TcTyVar]
+tcInstSigTyVars id_name scoped_names tyvars
+ = mapM new_tv tyvars
+ where
+ new_tv tv
+ = do { let name = tyVarName tv
+ ; ref <- newMutVar Flexi
+ ; name' <- if name `elem` scoped_names
+ then return name
+ else do { uniq <- newUnique; return (setNameUnique name uniq) }
+ ; return (mkTcTyVar name' (tyVarKind tv)
+ (SigSkolTv id_name ref)) }
+
+
+---------------------------------------------
+tcSkolType :: SkolemInfo -> TcType -> TcM ([TcTyVar], TcThetaType, TcType)
+-- Instantiate a type with fresh skolem constants
+tcSkolType info ty = tc_inst_type (tcSkolTyVars info) ty
+
+tcSkolTyVars :: SkolemInfo -> [TyVar] -> TcM [TcTyVar]
+tcSkolTyVars info tyvars
+ = do { us <- newUniqueSupply
+ ; return (zipWith skol_tv tyvars (uniqsFromSupply us)) }
+ where
+ skol_tv tv uniq = mkTcTyVar (setNameUnique (tyVarName tv) uniq)
+ (tyVarKind tv) (SkolemTv info)
+ -- See Note [TyVarName]
+
+
+---------------------------------------------
+tcSkolSigType :: SkolemInfo -> Type -> TcM ([TcTyVar], TcThetaType, TcType)
+-- Instantiate a type signature with skolem constants, but
+-- do *not* give them fresh names, because we want the name to
+-- be in the type environment -- it is lexically scoped.
+tcSkolSigType info ty
+ = tc_inst_type (\tvs -> return (tcSkolSigTyVars info tvs)) ty
+
+tcSkolSigTyVars :: SkolemInfo -> [TyVar] -> [TcTyVar]
+tcSkolSigTyVars info tyvars = [ mkTcTyVar (tyVarName tv) (tyVarKind tv) (SkolemTv info)
+ | tv <- tyvars ]
+
+-----------------------
+tc_inst_type :: ([TyVar] -> TcM [TcTyVar]) -- How to instantiate the type variables
+ -> TcType -- Type to instantiate
+ -> TcM ([TcTyVar], TcThetaType, TcType) -- Result
+tc_inst_type inst_tyvars ty
projects / ghc-hetmet.git / blobdiff