For pattern type sigs, we do want to bring those type variables into scope, even if there's a forall at the top which usually stops that happening, e.g:

\ (x :: forall a. a -> b) -> e

Here we do bring b into scope.

RULES can also use AlwaysBind, such as in the following example:

{-# RULES \"f\" forall (x :: forall a. a -> b). f x = ... b ... #-}

This only applies to RULES that do not explicitly bind their type variables. If a RULE explicitly quantifies its type variables, then NeverBind is used instead. See also Note [Pattern signature binders and scoping] in GHC.Hs.Type.

NeverBind

Never bind any free tyvars. This is used for RULES that have both explicit type and term variable binders, e.g.:

{-# RULES \"const\" forall a. forall (x :: a) y. const x y = x #-}

The presence of the type variable binder forall a. implies that the free variables in the types of the term variable binders x and y are not bound. In the example above, there are no such free variables, but if the user had written (y :: b) instead of y in the term variable binders, then b would be rejected for being out of scope. See also Note [Pattern signature binders and scoping] in GHC.Hs.Type.

rnHsSigWcType :: HsDocContext -> LHsSigWcType GhcPs -> RnM (LHsSigWcType GhcRn, FreeVars) Source #

rnHsPatSigType :: HsPatSigTypeScoping -> HsDocContext -> HsPatSigType GhcPs -> (HsPatSigType GhcRn -> RnM (a, FreeVars)) -> RnM (a, FreeVars) Source #

rnHsPatSigKind :: HsPatSigTypeScoping -> HsDocContext -> HsPatSigType GhcPs -> (HsPatSigType GhcRn -> RnM (a, FreeVars)) -> RnM (a, FreeVars) Source #

newTyVarNameRn :: Maybe a -> LocatedN RdrName -> RnM Name Source #

rnConDeclFields :: HsDocContext -> [FieldLabel] -> [LConDeclField GhcPs] -> RnM ([LConDeclField GhcRn], FreeVars) Source #

lookupField :: FastStringEnv FieldLabel -> FieldOcc GhcPs -> FieldOcc GhcRn Source #

mkHsOpTyRn :: PromotionFlag -> LocatedN Name -> Fixity -> LHsType GhcRn -> LHsType GhcRn -> RnM (HsType GhcRn) Source #

rnLTyVar :: LocatedN RdrName -> RnM (LocatedN Name) Source #

rnScaledLHsType :: HsDocContext -> HsScaled GhcPs (LHsType GhcPs) -> RnM (HsScaled GhcRn (LHsType GhcRn), FreeVars) Source #

data NegationHandling Source #

Constructors

ReassociateNegation
KeepNegationIntact

mkOpAppRn :: NegationHandling -> LHsExpr GhcRn -> LHsExpr GhcRn -> Fixity -> LHsExpr GhcRn -> RnM (HsExpr GhcRn) Source #

mkNegAppRn :: LHsExpr GhcRn -> SyntaxExpr GhcRn -> RnM (HsExpr GhcRn) Source #

mkConOpPatRn :: LocatedN Name -> Fixity -> LPat GhcRn -> LPat GhcRn -> RnM (Pat GhcRn) Source #

checkPrecMatch :: Name -> MatchGroup GhcRn body -> RnM () Source #

checkSectionPrec :: FixityDirection -> HsExpr GhcPs -> LHsExpr GhcRn -> LHsExpr GhcRn -> RnM () Source #

bindHsOuterTyVarBndrs Source #

Arguments

:: OutputableBndrFlag flag 'Renamed
=> HsDocContext
-> Maybe assoc	`Just _` => an associated type decl
-> FreeKiTyVars
-> HsOuterTyVarBndrs flag GhcPs
-> (HsOuterTyVarBndrs flag GhcRn -> RnM (a, FreeVars))
-> RnM (a, FreeVars)

bindHsForAllTelescope :: HsDocContext -> HsForAllTelescope GhcPs -> (HsForAllTelescope GhcRn -> RnM (a, FreeVars)) -> RnM (a, FreeVars) Source #

bindLHsTyVarBndr :: HsDocContext -> Maybe a -> LHsTyVarBndr flag GhcPs -> (LHsTyVarBndr flag GhcRn -> RnM (b, FreeVars)) -> RnM (b, FreeVars) Source #

bindLHsTyVarBndrs :: OutputableBndrFlag flag 'Renamed => HsDocContext -> WarnUnusedForalls -> Maybe a -> [LHsTyVarBndr flag GhcPs] -> ([LHsTyVarBndr flag GhcRn] -> RnM (b, FreeVars)) -> RnM (b, FreeVars) Source #

data WarnUnusedForalls Source #

Should GHC warn if a quantified type variable goes unused? Usually, the answer is "yes", but in the particular case of binding LHsQTyVars, we avoid emitting warnings. See Note [Suppress -Wunused-foralls when binding LHsQTyVars].

Constructors

WarnUnusedForalls
NoWarnUnusedForalls

Instances

Instances details

Outputable WarnUnusedForalls Source #
Instance details Defined in GHC.Rename.HsType Methods ppr :: WarnUnusedForalls -> SDoc Source #

rnImplicitTvOccs Source #

Arguments

:: Maybe assoc	`Just _` => an associated type decl
-> FreeKiTyVars	Surface-syntax free vars that we will implicitly bind. May have duplicates, which are removed here.
-> ([Name] -> RnM (a, FreeVars))
-> RnM (a, FreeVars)

Create new renamed type variables corresponding to source-level ones. Duplicates are permitted, but will be removed. This is intended especially for the case of handling the implicitly bound free variables of a type signature.

bindSigTyVarsFV :: [Name] -> RnM (a, FreeVars) -> RnM (a, FreeVars) Source #

bindHsQTyVars :: HsDocContext -> Maybe (a, [Name]) -> FreeKiTyVars -> LHsQTyVars GhcPs -> (LHsQTyVars GhcRn -> FreeKiTyVars -> RnM (b, FreeVars)) -> RnM (b, FreeVars) Source #

type FreeKiTyVars = [LocatedN RdrName] Source #

filterInScopeM :: FreeKiTyVars -> RnM FreeKiTyVars Source #

Filter out any type and kind variables that are already in scope in the the environment's LocalRdrEnv. Note that this includes named wildcards, which look like perfectly ordinary type variables at this point.

extractHsTyRdrTyVars :: LHsType GhcPs -> FreeKiTyVars Source #

extractHsTyRdrTyVars finds the type/kind variables of a HsType/HsKind. It's used when making the foralls explicit. See Note [Kind and type-variable binders]

extractHsTyRdrTyVarsKindVars :: LHsType GhcPs -> FreeKiTyVars Source #

Extracts the free type/kind variables from the kind signature of a HsType. This is used to implicitly quantify over k in type T = Nothing :: Maybe k. The left-to-right order of variables is preserved. See Note [Kind and type-variable binders] and Note [Ordering of implicit variables] and Note [Implicit quantification in type synonyms].

extractHsTysRdrTyVars :: [LHsType GhcPs] -> FreeKiTyVars -> FreeKiTyVars Source #

Extracts free type and kind variables from types in a list. When the same name occurs multiple times in the types, all occurrences are returned.

extractRdrKindSigVars :: LFamilyResultSig GhcPs -> FreeKiTyVars Source #

extractConDeclGADTDetailsTyVars :: HsConDeclGADTDetails GhcPs -> FreeKiTyVars -> FreeKiTyVars Source #

Extracts free type and kind variables from an argument in a GADT constructor, returning variable occurrences in left-to-right order. See Note [Ordering of implicit variables].

extractDataDefnKindVars :: HsDataDefn GhcPs -> FreeKiTyVars Source #

Get type/kind variables mentioned in the kind signature, preserving left-to-right order:

data T a (b :: k1) :: k2 -> k1 -> k2 -> Type -- result: [k2,k1]
data T a (b :: k1) -- result: []

See Note [Ordering of implicit variables].

extractHsOuterTvBndrs :: HsOuterTyVarBndrs flag GhcPs -> FreeKiTyVars -> FreeKiTyVars Source #

extractHsTyArgRdrKiTyVars :: [LHsTypeArg GhcPs] -> FreeKiTyVars Source #

nubL :: Eq a => [GenLocated l a] -> [GenLocated l a] Source #

nubN :: Eq a => [LocatedN a] -> [LocatedN a] Source #

badKindSigErr :: HsDocContext -> LHsType GhcPs -> TcM () Source #