RdrName

GHC uses several kinds of name internally:

• OccName: see OccName
• RdrName is the type of names that come directly from the parser. They have not yet had their scoping and binding resolved by the renamer and can be thought of to a first approximation as an OccName with an optional module qualifier
• Name: see Name
• Id: see Id
• Var: see Var

The main type

data RdrName

Reader Name

Do not use the data constructors of RdrName directly: prefer the family of functions that creates them, such as mkRdrUnqual

• Note: A Located RdrName will only have API Annotations if it is a compound one, e.g.

`bar`
( ~ )

• AnnKeywordId : AnnType, AnnOpen '(' or '[' or '[:', AnnClose ')' or ']' or ':]',, AnnBackquote '`', AnnVal AnnTilde,

Constructors

Unqual OccName

Unqualified name

Used for ordinary, unqualified occurrences, e.g. x, y or Foo. Create such a RdrName with mkRdrUnqual

Qual ModuleName OccName

Qualified name

A qualified name written by the user in source code. The module isn't necessarily the module where the thing is defined; just the one from which it is imported. Examples are Bar.x, Bar.y or Bar.Foo. Create such a RdrName with mkRdrQual

Orig Module OccName

Original name

An original name; the module is the defining module. This is used when GHC generates code that will be fed into the renamer (e.g. from deriving clauses), but where we want to say "Use Prelude.map dammit". One of these can be created with mkOrig

Exact Name

Exact name

We know exactly the Name. This is used:

1. When the parser parses built-in syntax like [] and (,), but wants a RdrName from it
2. By Template Haskell, when TH has generated a unique name

Such a RdrName can be created by using getRdrName on a Name

Instances

Eq RdrName

Defined in RdrName

Methods

(==) :: RdrName -> RdrName -> Bool

(/=) :: RdrName -> RdrName -> Bool

Data RdrName

Defined in RdrName

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> RdrName -> c RdrName

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c RdrName

toConstr :: RdrName -> Constr

dataTypeOf :: RdrName -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c RdrName)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c RdrName)

gmapT :: (forall b. Data b => b -> b) -> RdrName -> RdrName

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> RdrName -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> RdrName -> r

gmapQ :: (forall d. Data d => d -> u) -> RdrName -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> RdrName -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> RdrName -> m RdrName

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> RdrName -> m RdrName

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> RdrName -> m RdrName

Ord RdrName

Defined in RdrName

Methods

compare :: RdrName -> RdrName -> Ordering

(<) :: RdrName -> RdrName -> Bool

(<=) :: RdrName -> RdrName -> Bool

(>) :: RdrName -> RdrName -> Bool

(>=) :: RdrName -> RdrName -> Bool

max :: RdrName -> RdrName -> RdrName

min :: RdrName -> RdrName -> RdrName

OutputableBndr RdrName

Defined in RdrName

Methods

pprBndr :: BindingSite -> RdrName -> SDoc

pprPrefixOcc :: RdrName -> SDoc

pprInfixOcc :: RdrName -> SDoc

bndrIsJoin_maybe :: RdrName -> Maybe Int

Outputable RdrName

Defined in RdrName

Methods

ppr :: RdrName -> SDoc

pprPrec :: Rational -> RdrName -> SDoc

HasOccName RdrName

Defined in RdrName

Methods

occName :: RdrName -> OccName

Construction

mkRdrUnqual :: OccName -> RdrName

mkRdrQual :: ModuleName -> OccName -> RdrName

mkUnqual :: NameSpace -> FastString -> RdrName

mkVarUnqual :: FastString -> RdrName

mkQual :: NameSpace -> (FastString, FastString) -> RdrName

Make a qualified RdrName in the given namespace and where the ModuleName and the OccName are taken from the first and second elements of the tuple respectively

mkOrig :: Module -> OccName -> RdrName

nameRdrName :: Name -> RdrName

getRdrName :: NamedThing thing => thing -> RdrName

Destruction

rdrNameOcc :: RdrName -> OccName

rdrNameSpace :: RdrName -> NameSpace

demoteRdrName :: RdrName -> Maybe RdrName

isRdrDataCon :: RdrName -> Bool

isRdrTyVar :: RdrName -> Bool

isRdrTc :: RdrName -> Bool

isQual :: RdrName -> Bool

isQual_maybe :: RdrName -> Maybe (ModuleName, OccName)

isUnqual :: RdrName -> Bool

isOrig :: RdrName -> Bool

isOrig_maybe :: RdrName -> Maybe (Module, OccName)

isExact :: RdrName -> Bool

isExact_maybe :: RdrName -> Maybe Name

isSrcRdrName :: RdrName -> Bool

Local mapping of RdrName to Name

data LocalRdrEnv

Local Reader Environment

This environment is used to store local bindings (let, where, lambda, case). It is keyed by OccName, because we never use it for qualified names We keep the current mapping, *and* the set of all Names in scope Reason: see Note [Splicing Exact names] in RnEnv

Instances

Outputable LocalRdrEnv

Defined in RdrName

Methods

ppr :: LocalRdrEnv -> SDoc

pprPrec :: Rational -> LocalRdrEnv -> SDoc

emptyLocalRdrEnv :: LocalRdrEnv

extendLocalRdrEnv :: LocalRdrEnv -> Name -> LocalRdrEnv

extendLocalRdrEnvList :: LocalRdrEnv -> [Name] -> LocalRdrEnv

lookupLocalRdrEnv :: LocalRdrEnv -> RdrName -> Maybe Name

lookupLocalRdrOcc :: LocalRdrEnv -> OccName -> Maybe Name

elemLocalRdrEnv :: RdrName -> LocalRdrEnv -> Bool

inLocalRdrEnvScope :: Name -> LocalRdrEnv -> Bool

localRdrEnvElts :: LocalRdrEnv -> [Name]

delLocalRdrEnvList :: LocalRdrEnv -> [OccName] -> LocalRdrEnv

Global mapping of RdrName to GlobalRdrElts

type GlobalRdrEnv = OccEnv [GlobalRdrElt]

Global Reader Environment

Keyed by OccName; when looking up a qualified name we look up the OccName part, and then check the Provenance to see if the appropriate qualification is valid. This saves routinely doubling the size of the env by adding both qualified and unqualified names to the domain.

The list in the codomain is required because there may be name clashes These only get reported on lookup, not on construction

INVARIANT 1: All the members of the list have distinct gre_name fields; that is, no duplicate Names

INVARIANT 2: Imported provenance => Name is an ExternalName However LocalDefs can have an InternalName. This happens only when type-checking a [d| ... |] Template Haskell quotation; see this note in RnNames Note [Top-level Names in Template Haskell decl quotes]

INVARIANT 3: If the GlobalRdrEnv maps [occ -> gre], then greOccName gre = occ

NB: greOccName gre is usually the same as nameOccName (gre_name gre), but not always in the case of record seectors; see greOccName

emptyGlobalRdrEnv :: GlobalRdrEnv

mkGlobalRdrEnv :: [GlobalRdrElt] -> GlobalRdrEnv

plusGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrEnv -> GlobalRdrEnv

lookupGlobalRdrEnv :: GlobalRdrEnv -> OccName -> [GlobalRdrElt]

extendGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrElt -> GlobalRdrEnv

greOccName :: GlobalRdrElt -> OccName

shadowNames :: GlobalRdrEnv -> [Name] -> GlobalRdrEnv

pprGlobalRdrEnv :: Bool -> GlobalRdrEnv -> SDoc

globalRdrEnvElts :: GlobalRdrEnv -> [GlobalRdrElt]

lookupGRE_RdrName :: RdrName -> GlobalRdrEnv -> [GlobalRdrElt]

lookupGRE_Name :: GlobalRdrEnv -> Name -> Maybe GlobalRdrElt

Look for precisely this Name in the environment. This tests whether it is in scope, ignoring anything else that might be in scope with the same OccName.

lookupGRE_FieldLabel :: GlobalRdrEnv -> FieldLabel -> Maybe GlobalRdrElt

Look for a particular record field selector in the environment, where the selector name and field label may be different: the GlobalRdrEnv is keyed on the label. See Note [Parents for record fields] for why this happens.

lookupGRE_Name_OccName :: GlobalRdrEnv -> Name -> OccName -> Maybe GlobalRdrElt

Look for precisely this Name in the environment, but with an OccName that might differ from that of the Name. See lookupGRE_FieldLabel and Note [Parents for record fields].

getGRE_NameQualifier_maybes :: GlobalRdrEnv -> Name -> [Maybe [ModuleName]]

transformGREs :: (GlobalRdrElt -> GlobalRdrElt) -> [OccName] -> GlobalRdrEnv -> GlobalRdrEnv

Apply a transformation function to the GREs for these OccNames

pickGREs :: RdrName -> [GlobalRdrElt] -> [GlobalRdrElt]

Takes a list of GREs which have the right OccName x Pick those GREs that are in scope * Qualified, as x if want_qual is Qual M _ * Unqualified, as x if want_unqual is Unqual _

Return each such GRE, with its ImportSpecs filtered, to reflect how it is in scope qualified or unqualified respectively. See Note [GRE filtering]

pickGREsModExp :: ModuleName -> [GlobalRdrElt] -> [(GlobalRdrElt, GlobalRdrElt)]

Pick GREs that are in scope *both* qualified *and* unqualified Return each GRE that is, as a pair (qual_gre, unqual_gre) These two GREs are the original GRE with imports filtered to express how it is in scope qualified an unqualified respectively

Used only for the 'module M' item in export list; see RnNames.exports_from_avail

GlobalRdrElts

gresFromAvails :: Maybe ImportSpec -> [AvailInfo] -> [GlobalRdrElt]

make a GlobalRdrEnv where all the elements point to the same Provenance (useful for "hiding" imports, or imports with no details).

gresFromAvail :: (Name -> Maybe ImportSpec) -> AvailInfo -> [GlobalRdrElt]

localGREsFromAvail :: AvailInfo -> [GlobalRdrElt]

availFromGRE :: GlobalRdrElt -> AvailInfo

greRdrNames :: GlobalRdrElt -> [RdrName]

greSrcSpan :: GlobalRdrElt -> SrcSpan

greQualModName :: GlobalRdrElt -> ModuleName

gresToAvailInfo :: [GlobalRdrElt] -> [AvailInfo]

Takes a list of distinct GREs and folds them into AvailInfos. This is more efficient than mapping each individual GRE to an AvailInfo and the folding using plusAvail but needs the uniqueness assumption.

Global RdrName mapping elements: GlobalRdrElt, Provenance, ImportSpec

data GlobalRdrElt

Global Reader Element

An element of the GlobalRdrEnv

Constructors

GRE

Fields

• gre_name :: Name
• gre_par :: Parent
• gre_lcl :: Bool

  True = the thing was defined locally

• gre_imp :: [ImportSpec]

  In scope through these imports

Instances

Eq GlobalRdrElt

Defined in RdrName

Methods

(==) :: GlobalRdrElt -> GlobalRdrElt -> Bool

(/=) :: GlobalRdrElt -> GlobalRdrElt -> Bool

Data GlobalRdrElt

Defined in RdrName

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> GlobalRdrElt -> c GlobalRdrElt

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c GlobalRdrElt

toConstr :: GlobalRdrElt -> Constr

dataTypeOf :: GlobalRdrElt -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c GlobalRdrElt)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c GlobalRdrElt)

gmapT :: (forall b. Data b => b -> b) -> GlobalRdrElt -> GlobalRdrElt

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> GlobalRdrElt -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> GlobalRdrElt -> r

gmapQ :: (forall d. Data d => d -> u) -> GlobalRdrElt -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> GlobalRdrElt -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> GlobalRdrElt -> m GlobalRdrElt

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> GlobalRdrElt -> m GlobalRdrElt

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> GlobalRdrElt -> m GlobalRdrElt

Outputable GlobalRdrElt

Defined in RdrName

Methods

ppr :: GlobalRdrElt -> SDoc

pprPrec :: Rational -> GlobalRdrElt -> SDoc

isLocalGRE :: GlobalRdrElt -> Bool

isRecFldGRE :: GlobalRdrElt -> Bool

greLabel :: GlobalRdrElt -> Maybe FieldLabelString

unQualOK :: GlobalRdrElt -> Bool

Test if an unqualified version of this thing would be in scope

qualSpecOK :: ModuleName -> ImportSpec -> Bool

Is in scope qualified with the given module?

unQualSpecOK :: ImportSpec -> Bool

Is in scope unqualified?

pprNameProvenance :: GlobalRdrElt -> SDoc

Print out one place where the name was define/imported (With -dppr-debug, print them all)

data Parent

The children of a Name are the things that are abbreviated by the ".." notation in export lists. See Note [Parents]

Constructors

NoParent

ParentIs

Fields

• par_is :: Name

FldParent

See Note [Parents for record fields]

Fields

• par_is :: Name
• par_lbl :: Maybe FieldLabelString

Instances

Eq Parent

Defined in RdrName

Methods

(==) :: Parent -> Parent -> Bool

(/=) :: Parent -> Parent -> Bool

Data Parent

Defined in RdrName

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Parent -> c Parent

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Parent

toConstr :: Parent -> Constr

dataTypeOf :: Parent -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Parent)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Parent)

gmapT :: (forall b. Data b => b -> b) -> Parent -> Parent

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Parent -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Parent -> r

gmapQ :: (forall d. Data d => d -> u) -> Parent -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> Parent -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> Parent -> m Parent

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Parent -> m Parent

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Parent -> m Parent

Outputable Parent

Defined in RdrName

Methods

ppr :: Parent -> SDoc

pprPrec :: Rational -> Parent -> SDoc

greParent_maybe :: GlobalRdrElt -> Maybe Name

data ImportSpec

Import Specification

The ImportSpec of something says how it came to be imported It's quite elaborate so that we can give accurate unused-name warnings.

Constructors

ImpSpec

Fields

• is_decl :: ImpDeclSpec
• is_item :: ImpItemSpec

Instances

Eq ImportSpec

Defined in RdrName

Methods

(==) :: ImportSpec -> ImportSpec -> Bool

(/=) :: ImportSpec -> ImportSpec -> Bool

Data ImportSpec

Defined in RdrName

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> ImportSpec -> c ImportSpec

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c ImportSpec

toConstr :: ImportSpec -> Constr

dataTypeOf :: ImportSpec -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c ImportSpec)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c ImportSpec)

gmapT :: (forall b. Data b => b -> b) -> ImportSpec -> ImportSpec

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> ImportSpec -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> ImportSpec -> r

gmapQ :: (forall d. Data d => d -> u) -> ImportSpec -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> ImportSpec -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> ImportSpec -> m ImportSpec

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> ImportSpec -> m ImportSpec

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> ImportSpec -> m ImportSpec

Ord ImportSpec

Defined in RdrName

Methods

compare :: ImportSpec -> ImportSpec -> Ordering

(<) :: ImportSpec -> ImportSpec -> Bool

(<=) :: ImportSpec -> ImportSpec -> Bool

(>) :: ImportSpec -> ImportSpec -> Bool

(>=) :: ImportSpec -> ImportSpec -> Bool

max :: ImportSpec -> ImportSpec -> ImportSpec

min :: ImportSpec -> ImportSpec -> ImportSpec

Outputable ImportSpec

Defined in RdrName

Methods

ppr :: ImportSpec -> SDoc

pprPrec :: Rational -> ImportSpec -> SDoc

data ImpDeclSpec

Import Declaration Specification

Describes a particular import declaration and is shared among all the Provenances for that decl

Constructors

ImpDeclSpec

Fields

• is_mod :: ModuleName

  Module imported, e.g. import Muggle Note the Muggle may well not be the defining module for this thing!

• is_as :: ModuleName

  Import alias, e.g. from as M (or Muggle if there is no as clause)

• is_qual :: Bool

  Was this import qualified?

• is_dloc :: SrcSpan

  The location of the entire import declaration

Instances

Eq ImpDeclSpec

Defined in RdrName

Methods

(==) :: ImpDeclSpec -> ImpDeclSpec -> Bool

(/=) :: ImpDeclSpec -> ImpDeclSpec -> Bool

Data ImpDeclSpec

Defined in RdrName

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> ImpDeclSpec -> c ImpDeclSpec

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c ImpDeclSpec

toConstr :: ImpDeclSpec -> Constr

dataTypeOf :: ImpDeclSpec -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c ImpDeclSpec)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c ImpDeclSpec)

gmapT :: (forall b. Data b => b -> b) -> ImpDeclSpec -> ImpDeclSpec

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> ImpDeclSpec -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> ImpDeclSpec -> r

gmapQ :: (forall d. Data d => d -> u) -> ImpDeclSpec -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> ImpDeclSpec -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> ImpDeclSpec -> m ImpDeclSpec

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> ImpDeclSpec -> m ImpDeclSpec

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> ImpDeclSpec -> m ImpDeclSpec

Ord ImpDeclSpec

Defined in RdrName

Methods

compare :: ImpDeclSpec -> ImpDeclSpec -> Ordering

(<) :: ImpDeclSpec -> ImpDeclSpec -> Bool

(<=) :: ImpDeclSpec -> ImpDeclSpec -> Bool

(>) :: ImpDeclSpec -> ImpDeclSpec -> Bool

(>=) :: ImpDeclSpec -> ImpDeclSpec -> Bool

max :: ImpDeclSpec -> ImpDeclSpec -> ImpDeclSpec

min :: ImpDeclSpec -> ImpDeclSpec -> ImpDeclSpec

data ImpItemSpec

Import Item Specification

Describes import info a particular Name

Constructors

ImpAll

The import had no import list, or had a hiding list

ImpSome

The import had an import list. The is_explicit field is True iff the thing was named explicitly in the import specs rather than being imported as part of a "..." group. Consider:

import C( T(..) )

Here the constructors of T are not named explicitly; only T is named explicitly.

Fields

• is_explicit :: Bool
• is_iloc :: SrcSpan

Instances

Eq ImpItemSpec

Defined in RdrName

Methods

(==) :: ImpItemSpec -> ImpItemSpec -> Bool

(/=) :: ImpItemSpec -> ImpItemSpec -> Bool

Data ImpItemSpec

Defined in RdrName

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> ImpItemSpec -> c ImpItemSpec

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c ImpItemSpec

toConstr :: ImpItemSpec -> Constr

dataTypeOf :: ImpItemSpec -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c ImpItemSpec)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c ImpItemSpec)

gmapT :: (forall b. Data b => b -> b) -> ImpItemSpec -> ImpItemSpec

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> ImpItemSpec -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> ImpItemSpec -> r

gmapQ :: (forall d. Data d => d -> u) -> ImpItemSpec -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> ImpItemSpec -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> ImpItemSpec -> m ImpItemSpec

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> ImpItemSpec -> m ImpItemSpec

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> ImpItemSpec -> m ImpItemSpec

Ord ImpItemSpec

Defined in RdrName

Methods

compare :: ImpItemSpec -> ImpItemSpec -> Ordering

(<) :: ImpItemSpec -> ImpItemSpec -> Bool

(<=) :: ImpItemSpec -> ImpItemSpec -> Bool

(>) :: ImpItemSpec -> ImpItemSpec -> Bool

(>=) :: ImpItemSpec -> ImpItemSpec -> Bool

max :: ImpItemSpec -> ImpItemSpec -> ImpItemSpec

min :: ImpItemSpec -> ImpItemSpec -> ImpItemSpec

importSpecLoc :: ImportSpec -> SrcSpan

importSpecModule :: ImportSpec -> ModuleName

isExplicitItem :: ImpItemSpec -> Bool

bestImport :: [ImportSpec] -> ImportSpec

Utils for StarIsType

starInfo :: Bool -> RdrName -> SDoc

Display info about the treatment of * under NoStarIsType.

With StarIsType, three properties of * hold:

(a) it is not an infix operator (b) it is always in scope (c) it is a synonym for Data.Kind.Type

However, the user might not know that he's working on a module with NoStarIsType and write code that still assumes (a), (b), and (c), which actually do not hold in that module.

Violation of (a) shows up in the parser. For instance, in the following examples, we have * not applied to enough arguments:

data A :: * data F :: * -> *

Violation of (b) or (c) show up in the renamer and the typechecker respectively. For instance:

type K = Either * Bool

This will parse differently depending on whether StarIsType is enabled, but it will parse nonetheless. With NoStarIsType it is parsed as a type operator, thus we have ((*) Either Bool). Now there are two cases to consider:

1. There is no definition of (*) in scope. In this case the renamer will fail to look it up. This is a violation of assumption (b).
2. There is a definition of the (*) type operator in scope (for example coming from GHC.TypeNats). In this case the user will get a kind mismatch error. This is a violation of assumption (c).

The user might unknowingly be working on a module with NoStarIsType or use * as Type out of habit. So it is important to give a hint whenever an assumption about * is violated. Unfortunately, it is somewhat difficult to deal with (c), so we limit ourselves to (a) and (b).

starInfo generates an appropriate hint to the user depending on the extensions enabled in the module and the name that triggered the error. That is, if we have NoStarIsType and the error is related to * or its Unicode variant, the resulting SDoc will contain a helpful suggestion. Otherwise it is empty.