DataCon

:: Name
-> Bool	Is the constructor declared infix?
-> [StrictnessMark]	Strictness annotations written in the source file
-> [FieldLabel]	Field labels for the constructor, if it is a record, otherwise empty
-> [TyVar]	Universally quantified type variables
-> [TyVar]	Existentially quantified type variables
-> [(TyVar, Type)]	GADT equalities
-> ThetaType	Theta-type occuring before the arguments proper
-> [Type]	Argument types
-> TyCon	Type constructor we are for
-> ThetaType	The stupid theta, context of the data declaration e.g. `data Eq a => T a ...`
-> DataConIds	The Ids of the actual builder functions
-> DataCon
Build a new data constructor

fIRST_TAG :: ConTag

Tags are allocated from here for real constructors

Type deconstruction

dataConRepType :: DataCon -> Type

The representation type of the data constructor, i.e. the sort type that will represent values of this type at runtime

dataConSig :: DataCon -> ([TyVar], ThetaType, [Type], Type)

The "signature" of the DataCon returns, in order:

1) The result of dataConAllTyVars,

2) All the ThetaTypes relating to the DataCon (coercion, dictionary, implicit parameter - whatever)

3) The type arguments to the constructor

4) The original result type of the DataCon

dataConFullSig :: DataCon -> ([TyVar], [TyVar], [(TyVar, Type)], ThetaType, ThetaType, [Type], Type)

The "full signature" of the DataCon returns, in order:

1) The result of dataConUnivTyVars

2) The result of dataConExTyVars

3) The result of dataConEqSpec

4) The result of dataConDictTheta

5) The original argument types to the DataCon (i.e. before any change of the representation of the type)

6) The original result type of the DataCon

dataConName :: DataCon -> Name

The Name of the DataCon, giving it a unique, rooted identification

dataConIdentity :: DataCon -> [Word8]

The string package:module.name identifying a constructor, which is attached to its info table and used by the GHCi debugger and the heap profiler

dataConTag :: DataCon -> ConTag

The tag used for ordering DataCons

dataConTyCon :: DataCon -> TyCon

The type constructor that we are building via this data constructor

dataConUserType :: DataCon -> Type

The user-declared type of the data constructor in the nice-to-read form:

 T :: forall a b. a -> b -> T [a]

rather than:

 T :: forall a c. forall b. (c=[a]) => a -> b -> T c

NB: If the constructor is part of a data instance, the result type mentions the family tycon, not the internal one.

dataConUnivTyVars :: DataCon -> [TyVar]

The universally-quantified type variables of the constructor

dataConExTyVars :: DataCon -> [TyVar]

The existentially-quantified type variables of the constructor

dataConAllTyVars :: DataCon -> [TyVar]

Both the universal and existentiatial type variables of the constructor

dataConEqSpec :: DataCon -> [(TyVar, Type)]

Equalities derived from the result type of the data constructor, as written by the programmer in any GADT declaration

eqSpecPreds :: [(TyVar, Type)] -> ThetaType

dataConEqTheta :: DataCon -> ThetaType

The equational constraints on the data constructor type

dataConDictTheta :: DataCon -> ThetaType

The type class and implicit parameter contsraints on the data constructor type

dataConStupidTheta :: DataCon -> ThetaType

The "stupid theta" of the DataCon, such as data Eq a in:

 data Eq a => T a = ...

dataConInstArgTys

:: DataCon	A datacon with no existentials or equality constraints However, it can have a dcTheta (notably it can be a class dictionary, with superclasses)
-> [Type]	Instantiated at these types
-> [Type]
Finds the instantiated types of the arguments required to construct a `DataCon` representation NB: these INCLUDE any dictionary args but EXCLUDE the data-declaration context, which is discarded It's all post-flattening etc; this is a representation type

dataConOrigArgTys :: DataCon -> [Type]

Returns the argument types of the wrapper, excluding all dictionary arguments and without substituting for any type variables

dataConOrigResTy :: DataCon -> Type

dataConInstOrigArgTys :: DataCon -> [Type] -> [Type]

Returns just the instantiated value argument types of a DataCon, (excluding dictionary args)

dataConRepArgTys :: DataCon -> [Type]

Returns the arg types of the worker, including all dictionaries, after any flattening has been done and without substituting for any type variables

dataConFieldLabels :: DataCon -> [FieldLabel]

The labels for the fields of this particular DataCon

dataConFieldType :: DataCon -> FieldLabel -> Type

Extract the type for any given labelled field of the DataCon

dataConStrictMarks :: DataCon -> [StrictnessMark]

The strictness markings decided on by the compiler. Does not include those for existential dictionaries. The list is in one-to-one correspondence with the arity of the DataCon

dataConExStricts :: DataCon -> [StrictnessMark]

Strictness of existential arguments only

dataConSourceArity :: DataCon -> Arity

Source-level arity of the data constructor

dataConRepArity :: DataCon -> Int

Gives the number of actual fields in the representation of the data constructor. This may be more than appear in the source code; the extra ones are the existentially quantified dictionaries

dataConIsInfix :: DataCon -> Bool

Should the DataCon be presented infix?

dataConWorkId :: DataCon -> Id

Get the Id of the DataCon worker: a function that is the actual constructor and has no top level binding in the program. The type may be different from the obvious one written in the source program. Panics if there is no such Id for this DataCon

dataConWrapId :: DataCon -> Id

Returns an Id which looks like the Haskell-source constructor by using the wrapper if it exists (see dataConWrapId_maybe) and failing over to the worker (see dataConWorkId)

dataConWrapId_maybe :: DataCon -> Maybe Id

Get the Id of the DataCon wrapper: a function that wraps the actual constructor so it has the type visible in the source program: c.f. dataConWorkId. Returns Nothing if there is no wrapper, which occurs for an algebraic data constructor and also for a newtype (whose constructor is inlined compulsorily)

dataConImplicitIds :: DataCon -> [Id]

Find all the Ids implicitly brought into scope by the data constructor. Currently, the union of the dataConWorkId and the dataConWrapId

dataConRepStrictness :: DataCon -> [StrictnessMark]

Give the demands on the arguments of a Core constructor application (Con dc args)

Predicates on DataCons

isNullarySrcDataCon :: DataCon -> Bool

Return whether there are any argument types for this DataCons original source type

isNullaryRepDataCon :: DataCon -> Bool

Return whether there are any argument types for this DataCons runtime representation type

isTupleCon :: DataCon -> Bool

isUnboxedTupleCon :: DataCon -> Bool

isVanillaDataCon :: DataCon -> Bool

Vanilla DataCons are those that are nice boring Haskell 98 constructors

classDataCon :: Class -> DataCon

Splitting product types

splitProductType_maybe

:: Type A product type, perhaps

-> Maybe (TyCon, [Type], DataCon, [Type])

Extract the type constructor, type argument, data constructor and it's representation argument types from a type if it is a product type.

Precisely, we return Just for any type that is all of:

Concrete (i.e. constructors visible)
Single-constructor
Not existentially quantified

Whether the type is a data type or a newtype

splitProductType :: String -> Type -> (TyCon, [Type], DataCon, [Type])

As splitProductType_maybe, but panics if the Type is not a product type

deepSplitProductType :: String -> Type -> (TyCon, [Type], DataCon, [Type])

As deepSplitProductType_maybe, but panics if the Type is not a product type

deepSplitProductType_maybe :: Type -> Maybe (TyCon, [Type], DataCon, [Type])

As splitProductType_maybe, but in turn instantiates the TyCon returned and hence recursively tries to unpack it as far as it able to

Produced by Haddock version 2.3.0