GHC.Rename.HsType

Documentation

rnHsType :: HsDocContext -> HsType GhcPs -> RnM (HsType GhcRn, FreeVars)

rnLHsType :: HsDocContext -> LHsType GhcPs -> RnM (LHsType GhcRn, FreeVars)

rnLHsTypes :: HsDocContext -> [LHsType GhcPs] -> RnM ([LHsType GhcRn], FreeVars)

rnContext :: HsDocContext -> LHsContext GhcPs -> RnM (LHsContext GhcRn, FreeVars)

rnHsKind :: HsDocContext -> HsKind GhcPs -> RnM (HsKind GhcRn, FreeVars)

rnLHsKind :: HsDocContext -> LHsKind GhcPs -> RnM (LHsKind GhcRn, FreeVars)

rnLHsTypeArgs :: HsDocContext -> [LHsTypeArg GhcPs] -> RnM ([LHsTypeArg GhcRn], FreeVars)

rnHsSigType :: HsDocContext -> TypeOrKind -> LHsSigType GhcPs -> RnM (LHsSigType GhcRn, FreeVars)

rnHsWcType :: HsDocContext -> LHsWcType GhcPs -> RnM (LHsWcType GhcRn, FreeVars)

data HsSigWcTypeScoping

Constructors

AlwaysBind

Always bind any free tyvars of the given type, regardless of whether we have a forall at the top.

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.

BindUnlessForall

Unless there's forall at the top, do the same thing as AlwaysBind. This is only ever used in places where the "forall-or-nothing" rule is in effect. See Note [forall-or-nothing rule].

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)

rnHsPatSigType :: HsSigWcTypeScoping -> HsDocContext -> HsPatSigType GhcPs -> (HsPatSigType GhcRn -> RnM (a, FreeVars)) -> RnM (a, FreeVars)

newTyVarNameRn :: Maybe a -> Located RdrName -> RnM Name

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

rnLTyVar :: Located RdrName -> RnM (Located Name)

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

mkOpAppRn :: LHsExpr GhcRn -> LHsExpr GhcRn -> Fixity -> LHsExpr GhcRn -> RnM (HsExpr GhcRn)

mkNegAppRn :: LHsExpr (GhcPass id) -> SyntaxExpr (GhcPass id) -> RnM (HsExpr (GhcPass id))

mkOpFormRn :: LHsCmdTop GhcRn -> LHsExpr GhcRn -> Fixity -> LHsCmdTop GhcRn -> RnM (HsCmd GhcRn)

mkConOpPatRn :: Located Name -> Fixity -> LPat GhcRn -> LPat GhcRn -> RnM (Pat GhcRn)

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

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

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

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

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

data WarnUnusedForalls

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

Outputable WarnUnusedForalls

Defined in GHC.Rename.HsType

Methods

ppr :: WarnUnusedForalls -> SDoc

pprPrec :: Rational -> WarnUnusedForalls -> SDoc

rnImplicitBndrs

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)

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

bindHsQTyVars :: forall a b. HsDocContext -> Maybe a -> FreeKiTyVars -> LHsQTyVars GhcPs -> (LHsQTyVars GhcRn -> Bool -> RnM (b, FreeVars)) -> RnM (b, FreeVars)

type FreeKiTyVars = [Located RdrName]

extractHsTyRdrTyVars :: LHsType GhcPs -> FreeKiTyVars

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

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

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

extractDataDefnKindVars :: HsDataDefn GhcPs -> FreeKiTyVars

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].

extractHsTvBndrs :: [LHsTyVarBndr flag GhcPs] -> FreeKiTyVars -> FreeKiTyVars

extractHsTyArgRdrKiTyVars :: [LHsTypeArg GhcPs] -> FreeKiTyVars

extractHsScaledTysRdrTyVars :: [HsScaled GhcPs (LHsType GhcPs)] -> FreeKiTyVars -> FreeKiTyVars

forAllOrNothing

Arguments

:: Bool

True = explicit forall E.g. f :: forall a. a->b we do not want to bring b into scope, hence True But f :: a -> b we want to bring both a and b into scope, hence False

-> FreeKiTyVars

Free vars of the type

-> RnM FreeKiTyVars

See Note [forall-or-nothing rule]. This tiny little function is used (rather than its small body inlined) to indicate that we are implementing that rule.

nubL :: Eq a => [Located a] -> [Located a]