Moduleghc-lib-parser-9.14.1.20251220GHC2021

GHC.Hs.Pat

15 types
26 values

Packageghc-lib-parser-9.14.1.20251220
Exports42
LanguageGHC2021
LicenceBSD-3-Clause
SourcePat.hs

datadata Pat p

Pattern

Constructors

WildPat (XWildPat p)
Wildcard Pattern, i.e. _
VarPat (XVarPat p) (LIdP p)
Variable Pattern, e.g. x
LazyPat (XLazyPat p) (LPat p)
Lazy Pattern, e.g. ~x
AsPat (XAsPat p) (LIdP p) (LPat p)
As pattern, e.g. x@pat
ParPat (XParPat p) (LPat p)
Parenthesised pattern, e.g. (x)
BangPat (XBangPat p) (LPat p)
Bang pattern, e.g. !x
ListPat (XListPat p) [LPat p]
Syntactic List, e.g. [x] or [x,y]. Note that [] and (x:xs) patterns are both represented using ConPat.
TuplePat (XTuplePat p) [LPat p] Boxity
Tuple pattern, e.g. (x, y) (boxed tuples) or (# x, y #) (requires -XUnboxedTuples)
OrPat (XOrPat p) (NonEmpty (LPat p))
Or Pattern, e.g. (pat_1; ...; pat_n). Used by -XOrPatterns
SumPat (XSumPat p) (LPat p) ConTag SumWidth
Anonymous sum pattern, e.g. (# x | #). Used by -XUnboxedSums
ConPat
Constructor Pattern, e.g. (), [] or Nothing
- pat_con_ext :: XConPat p
- pat_con :: XRec p (ConLikeP p)
- pat_args :: HsConPatDetails p
ViewPat (XViewPat p) (LHsExpr p) (LPat p)
View Pattern, e.g. someFun -> pat. Used by -XViewPatterns
SplicePat (XSplicePat p) (HsUntypedSplice p)
Splice Pattern, e.g. $(pat)
LitPat (XLitPat p) (HsLit p)
Literal Pattern
Used for non-overloaded literal patterns: Int#, Char#, Int, Char, String, etc.
NPat (XNPat p) (XRec p (HsOverLit p)) (Maybe (SyntaxExpr p)) (SyntaxExpr p)
Natural Pattern, used for all overloaded literals, including overloaded Strings with -XOverloadedStrings
NPlusKPat (XNPlusKPat p) (LIdP p) (XRec p (HsOverLit p)) (HsOverLit p) (SyntaxExpr p) (SyntaxExpr p)
n+k pattern, e.g. n+1, used by -XNPlusKPatterns
SigPat (XSigPat p) (LPat p) (HsPatSigType (NoGhcTc p))
Pattern with a type signature, e.g. x :: Int
EmbTyPat (XEmbTyPat p) (HsTyPat (NoGhcTc p))
Embed the syntax of types into patterns, e.g. fn (type t) = rhs. Enabled by -XExplicitNamespaces in conjunction with -XRequiredTypeArguments.
InvisPat (XInvisPat p) (HsTyPat (NoGhcTc p))
Type abstraction which brings into scope type variables associated with invisible forall. E.g. fn @t ... = rhs. Used by -XTypeAbstractions.
XPat !(XXPat p)
TTG Extension point; see Note [Trees That Grow] in Language.Haskell.Syntax.Extension

Instances9Data, Outputable, CollectBinders, CollectFldBinders, Anno, …

Data (Pat GhcPs)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Instances · orphan
Data (Pat GhcRn)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Instances · orphan
Data (Pat GhcTc)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Instances · orphan
OutputableBndrId p => Outputable (Pat (GhcPass p))Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat · orphan
CollectBinders (LocatedA (Pat GhcTc))Defined in ghc-lib-parser-9.14.1.20251220 · GHC.HsToCore.Ticks
CollectBinders [LocatedA (Pat GhcTc)]Defined in ghc-lib-parser-9.14.1.20251220 · GHC.HsToCore.Ticks
CollectFldBinders (Pat GhcTc)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.HsToCore.Ticks
type Anno (Pat (GhcPass p)) = SrcSpanAnnADefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat · orphan
type Anno [LocatedA (Pat (GhcPass p))] = EpaLocationDefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Expr · orphan

typetype LPat p = XRec p (Pat p)

valueisInvisArgPat :: Pat p -> Bool

valueisInvisArgLPat :: UnXRec p => LPat p -> Bool

valueisVisArgPat :: Pat p -> Bool

valueisVisArgLPat :: UnXRec p => LPat p -> Bool

datadata EpAnnSumPat

Constructors

EpAnnSumPat
- sumPatParens :: (EpaLocation, EpaLocation)
- sumPatVbarsBefore :: [EpToken "|"]
- sumPatVbarsAfter :: [EpToken "|"]

Instances2Data, NoAnn

Data EpAnnSumPatDefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat
NoAnn EpAnnSumPatDefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat

datadata ConPatTc

This is the extension field for ConPat, added after typechecking It adds quite a few extra fields, to support elaboration of pattern matching.

Constructors

ConPatTc
- cpt_arg_tys :: [Type]
  The universal arg types 1-1 with the universal tyvars of the constructor/pattern synonym Use (conLikeResTy pat_con cpt_arg_tys) to get the type of the pattern
- cpt_tvs :: [TyVar]
  Existentially bound type variables in correctly-scoped order e.g. [k:* x:k]
- cpt_dicts :: [EvVar]
  Ditto *coercion variables* and *dictionaries* One reason for putting coercion variable here I think is to ensure their kinds are zonked
- cpt_binds :: TcEvBinds
  Bindings involving those dictionaries
- cpt_wrap :: HsWrapper
  Extra wrapper to pass to the matcher Only relevant for pattern-synonyms; ignored for data cons

Instances1Data

Data ConPatTcDefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Instances · orphan

familytype family ConLikeP x

Instances3ConLikeP

type ConLikeP GhcPs = RdrNameDefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat · orphan
type ConLikeP GhcRn = WithUserRdr NameDefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat · orphan
type ConLikeP GhcTc = ConLikeDefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat · orphan

datadata HsPatExpansion a b

Constructors

HsPatExpanded a b

Instances2Data, Outputable

(Data a, Data b) => Data (HsPatExpansion a b)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat
(Outputable a, Outputable b) => Outputable (HsPatExpansion a b)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat

datadata XXPatGhcTc

Extension constructor for Pat, added after typechecking.

Constructors

CoPat
Coercion Pattern (translation only)
During desugaring a (CoPat co pat) turns into a cast with co on the scrutinee, followed by a match on pat.
- co_cpt_wrap :: HsWrapper
  Coercion Pattern If co :: t1 ~ t2, p :: t2, then (CoPat co p) :: t1
- co_pat_inner :: Pat GhcTc
  Why not LPat? Ans: existing locn will do
- co_pat_ty :: Type
  Type of whole pattern, t1
ExpansionPat (Pat GhcRn) (Pat GhcTc)
Pattern expansion: original pattern, and desugared pattern, for RebindableSyntax and other overloaded syntax such as OverloadedLists. See Note [Rebindable syntax and XXExprGhcRn].

Instances2Data, CollectFldBinders

Data XXPatGhcTcDefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Instances · orphan
CollectFldBinders XXPatGhcTcDefined in ghc-lib-parser-9.14.1.20251220 · GHC.HsToCore.Ticks

typetype HsConPatDetails p = HsConDetails (LPat p) (HsRecFields p (LPat p))

Haskell Constructor Pattern Details

valuehsConPatArgs :: UnXRec p => HsConPatDetails p -> [LPat p]

datadata HsRecFields p arg

Haskell Record Fields

HsRecFields is used only for patterns and expressions (not data type declarations)

Constructors

HsRecFields
- rec_ext :: !XHsRecFields p
- rec_flds :: [LHsRecField p arg]
- rec_dotdot :: Maybe (XRec p RecFieldsDotDot)

Instances4Data, Outputable

Data body => Data (HsRecFields GhcPs body)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Instances · orphan
Data body => Data (HsRecFields GhcRn body)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Instances · orphan
Data body => Data (HsRecFields GhcTc body)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Instances · orphan
(Outputable arg, Outputable (XRec p (HsRecField p arg)), XRec p RecFieldsDotDot ~ LocatedE RecFieldsDotDot) => Outputable (HsRecFields p arg)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat · orphan

datadata HsFieldBind lhs rhs

Haskell Field Binding

Constructors

HsFieldBind
- hfbAnn :: XHsFieldBind lhs
- hfbLHS :: lhs
- hfbRHS :: rhs
  Filled in by renamer when punning
- hfbPun :: Bool
  Note [Punning]

Instances7Functor, Foldable, Traversable, Data, Outputable, CollectFldBinders, …

Functor (HsFieldBind lhs)Defined in ghc-lib-parser-9.14.1.20251220 · Language.Haskell.Syntax.Pat
Foldable (HsFieldBind lhs)Defined in ghc-lib-parser-9.14.1.20251220 · Language.Haskell.Syntax.Pat
Traversable (HsFieldBind lhs)Defined in ghc-lib-parser-9.14.1.20251220 · Language.Haskell.Syntax.Pat
(Data a, Data b) => Data (HsFieldBind a b)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Instances · orphan
(Outputable p, OutputableBndr p, Outputable arg) => Outputable (HsFieldBind p arg)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat · orphan
CollectFldBinders r => CollectFldBinders (HsFieldBind l r)Defined in ghc-lib-parser-9.14.1.20251220 · GHC.HsToCore.Ticks
type Anno (HsFieldBind lhs rhs) = SrcSpanAnnADefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat · orphan

typetype LHsFieldBind p id arg = XRec p (HsFieldBind id arg)

Located Haskell Record Field

typetype HsRecField p arg = HsFieldBind (LFieldOcc p) arg

Haskell Record Field

typetype LHsRecField p arg = XRec p (HsRecField p arg)

Located Haskell Record Field

typetype HsRecUpdField p q = HsFieldBind (LFieldOcc p) (LHsExpr q)

Haskell Record Update Field

typetype LHsRecUpdField p q = XRec p (HsRecUpdField p q)

Located Haskell Record Update Field

newtypenewtype RecFieldsDotDot

Newtype to be able to have a specific XRec instance for the Int in rec_dotdot

Constructors

RecFieldsDotDot
- unRecFieldsDotDot :: Int

Instances4Eq, Data, Ord, Anno

Eq RecFieldsDotDotDefined in ghc-lib-parser-9.14.1.20251220 · Language.Haskell.Syntax.Pat
Data RecFieldsDotDotDefined in ghc-lib-parser-9.14.1.20251220 · Language.Haskell.Syntax.Pat
Ord RecFieldsDotDotDefined in ghc-lib-parser-9.14.1.20251220 · Language.Haskell.Syntax.Pat
type Anno RecFieldsDotDot = EpaLocationDefined in ghc-lib-parser-9.14.1.20251220 · GHC.Hs.Pat · orphan

valuehsRecFields :: HsRecFields (GhcPass p) arg -> [IdGhcP p]

valuehsRecFieldSel :: HsRecField (GhcPass p) arg -> IdGhcP p

valuehsRecFieldId :: HsRecField GhcTc arg -> Id

valuehsRecFieldsArgs :: HsRecFields (GhcPass p) arg -> [arg]

valuemkPrefixConPat :: DataCon -> [LPat GhcTc] -> [Type] -> LPat GhcTc

valuemkCharLitPat :: SourceText -> Char -> LPat GhcTc

valuemkNilPat :: Type -> LPat GhcTc

valueisSimplePat :: LPat (GhcPass x) -> Maybe (IdP (GhcPass x))

Is the pattern any of combination of:

(pat)
pat :: Type
~pat
!pat
x (variable)

valueisPatSyn :: LPat GhcTc -> Bool

valuelooksLazyPatBind :: HsBind GhcTc -> Bool

valueisBangedLPat :: LPat (GhcPass p) -> Bool

valuegParPat :: IsPass p => LPat (GhcPass p) -> Pat (GhcPass p)

Parenthesize a pattern without token information

valuepatNeedsParens :: IsPass p => PprPrec -> Pat (GhcPass p) -> Bool

patNeedsParens p pat returns True if the pattern pat needs parentheses under precedence p.

valueparenthesizePat

:: IsPass p
=> PprPrec
-> LPat (GhcPass p)
-> LPat (GhcPass p)

parenthesizePat p pat checks if patNeedsParens p pat is true, and if so, surrounds pat with a ParPat. Otherwise, it simply returns pat.

valueisIrrefutableHsPat

:: IsPass p
=> Bool
Are we in a -XStrict context? See Note [-XStrict and irrefutability]
-> (ConLikeP (GhcPass p) -> Bool)
How to check whether the ConLike in a ConPat pattern is irrefutable
-> LPat (GhcPass p)
The (located) pattern to check
-> Bool

isIrrefutableHsPat p is true if matching against p cannot fail in the sense of falling through to the next pattern. (NB: this is not quite the same as the (silly) defn in 3.17.2 of the Haskell 98 report.)

If isIrrefutableHsPat returns True, the pattern is definitely irrefutable.

However, isIrrefutableHsPat returns False if it's in doubt. It's a best effort guess with the information we have available:

we sometimes call isIrrefutableHsPat from the renamer, in which case we don't have type information to hand. This means we can't properly handle GADTs, nor the result TyCon of COMPLETE pragmas.
even when calling isIrrefutableHsPat in the typechecker, we don't keep track of any long distance information like the pattern-match checker does.

valueisBoringHsPat :: OutputableBndrId p => LPat (GhcPass p) -> Bool

Is this pattern boring from the perspective of pattern-match checking, i.e. introduces no new pieces of long-distance information which could influence pattern-match checking?

See Note [Boring patterns].

valuecollectEvVarsPat :: Pat GhcTc -> Bag EvVar

valuecollectEvVarsPats :: [Pat GhcTc] -> Bag EvVar

valuepprParendLPat :: OutputableBndrId p => PprPrec -> LPat (GhcPass p) -> SDoc

valuepprConArgs

:: (OutputableBndrId p, Outputable (Anno (IdGhcP p)))
=> HsConPatDetails (GhcPass p)
-> SDoc

valuepprLPat :: OutputableBndrId p => LPat (GhcPass p) -> SDoc

Orphan instances

3 instances

OutputableBndrId p => Outputable (Pat (GhcPass p))
(Outputable arg, Outputable (XRec p (HsRecField p arg)), XRec p RecFieldsDotDot ~ LocatedE RecFieldsDotDot) => Outputable (HsRecFields p arg)
(Outputable p, OutputableBndr p, Outputable arg) => Outputable (HsFieldBind p arg)