Safe Haskell | Safe-Infered |
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DataCon
Contents
- data DataCon
- data DataConIds = DCIds (Maybe Id) Id
- type ConTag = Int
- mkDataCon :: Name -> Bool -> [HsBang] -> [FieldLabel] -> [TyVar] -> [TyVar] -> [(TyVar, Type)] -> ThetaType -> [Type] -> Type -> TyCon -> ThetaType -> DataConIds -> DataCon
- fIRST_TAG :: ConTag
- dataConRepType :: DataCon -> Type
- dataConSig :: DataCon -> ([TyVar], ThetaType, [Type], Type)
- dataConFullSig :: DataCon -> ([TyVar], [TyVar], [(TyVar, Type)], ThetaType, [Type], Type)
- dataConName :: DataCon -> Name
- dataConIdentity :: DataCon -> [Word8]
- dataConTag :: DataCon -> ConTag
- dataConTyCon :: DataCon -> TyCon
- dataConOrigTyCon :: DataCon -> TyCon
- dataConUserType :: DataCon -> Type
- dataConUnivTyVars :: DataCon -> [TyVar]
- dataConExTyVars :: DataCon -> [TyVar]
- dataConAllTyVars :: DataCon -> [TyVar]
- dataConEqSpec :: DataCon -> [(TyVar, Type)]
- eqSpecPreds :: [(TyVar, Type)] -> ThetaType
- dataConTheta :: DataCon -> ThetaType
- dataConStupidTheta :: DataCon -> ThetaType
- dataConInstArgTys :: DataCon -> [Type] -> [Type]
- dataConOrigArgTys :: DataCon -> [Type]
- dataConOrigResTy :: DataCon -> Type
- dataConInstOrigArgTys :: DataCon -> [Type] -> [Type]
- dataConRepArgTys :: DataCon -> [Type]
- dataConFieldLabels :: DataCon -> [FieldLabel]
- dataConFieldType :: DataCon -> FieldLabel -> Type
- dataConStrictMarks :: DataCon -> [HsBang]
- dataConExStricts :: DataCon -> [HsBang]
- dataConSourceArity :: DataCon -> Arity
- dataConRepArity :: DataCon -> Int
- dataConIsInfix :: DataCon -> Bool
- dataConWorkId :: DataCon -> Id
- dataConWrapId :: DataCon -> Id
- dataConWrapId_maybe :: DataCon -> Maybe Id
- dataConImplicitIds :: DataCon -> [Id]
- dataConRepStrictness :: DataCon -> [StrictnessMark]
- isNullarySrcDataCon :: DataCon -> Bool
- isNullaryRepDataCon :: DataCon -> Bool
- isTupleCon :: DataCon -> Bool
- isUnboxedTupleCon :: DataCon -> Bool
- isVanillaDataCon :: DataCon -> Bool
- classDataCon :: Class -> DataCon
- dataConCannotMatch :: [Type] -> DataCon -> Bool
- splitProductType_maybe :: Type -> Maybe (TyCon, [Type], DataCon, [Type])
- splitProductType :: String -> Type -> (TyCon, [Type], DataCon, [Type])
- deepSplitProductType :: String -> Type -> (TyCon, [Type], DataCon, [Type])
- deepSplitProductType_maybe :: Type -> Maybe (TyCon, [Type], DataCon, [Type])
Main data types
A data constructor
data DataConIds Source
Contains the Ids of the data constructor functions
Type construction
Arguments
:: Name | |
-> Bool | Is the constructor declared infix? |
-> [HsBang] | 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] | Original argument types |
-> Type | Original result type |
-> TyCon | Representation type constructor |
-> ThetaType | The stupid theta, context of the data declaration
e.g. |
-> DataConIds | The Ids of the actual builder functions |
-> DataCon |
Build a new data constructor
Type deconstruction
dataConRepType :: DataCon -> TypeSource
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)Source
The "signature" of the DataCon
returns, in order:
1) The result of dataConAllTyVars
,
2) All the ThetaType
s 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, [Type], Type)Source
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 -> NameSource
dataConIdentity :: DataCon -> [Word8]Source
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 -> ConTagSource
The tag used for ordering DataCon
s
dataConTyCon :: DataCon -> TyConSource
The type constructor that we are building via this data constructor
dataConOrigTyCon :: DataCon -> TyConSource
The original type constructor used in the definition of this data constructor. In case of a data family instance, that will be the family type constructor.
dataConUserType :: DataCon -> TypeSource
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]Source
The universally-quantified type variables of the constructor
dataConExTyVars :: DataCon -> [TyVar]Source
The existentially-quantified type variables of the constructor
dataConAllTyVars :: DataCon -> [TyVar]Source
Both the universal and existentiatial type variables of the constructor
dataConEqSpec :: DataCon -> [(TyVar, Type)]Source
Equalities derived from the result type of the data constructor, as written by the programmer in any GADT declaration
eqSpecPreds :: [(TyVar, Type)] -> ThetaTypeSource
dataConTheta :: DataCon -> ThetaTypeSource
The *full* constraints on the constructor type
dataConStupidTheta :: DataCon -> ThetaTypeSource
The "stupid theta" of the DataCon
, such as data Eq a
in:
data Eq a => T a = ...
Arguments
:: 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]Source
Returns the argument types of the wrapper, excluding all dictionary arguments and without substituting for any type variables
dataConInstOrigArgTys :: DataCon -> [Type] -> [Type]Source
Returns just the instantiated value argument types of a DataCon
,
(excluding dictionary args)
dataConRepArgTys :: DataCon -> [Type]Source
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]Source
The labels for the fields of this particular DataCon
dataConFieldType :: DataCon -> FieldLabel -> TypeSource
Extract the type for any given labelled field of the DataCon
dataConStrictMarks :: DataCon -> [HsBang]Source
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 -> [HsBang]Source
Strictness of evidence arguments to the wrapper function
dataConSourceArity :: DataCon -> AritySource
Source-level arity of the data constructor
dataConRepArity :: DataCon -> IntSource
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 -> BoolSource
Should the DataCon
be presented infix?
dataConWorkId :: DataCon -> IdSource
dataConWrapId :: DataCon -> IdSource
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 IdSource
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]Source
Find all the Id
s implicitly brought into scope by the data constructor. Currently,
the union of the dataConWorkId
and the dataConWrapId
dataConRepStrictness :: DataCon -> [StrictnessMark]Source
Give the demands on the arguments of a Core constructor application (Con dc args)
Predicates on DataCons
isNullarySrcDataCon :: DataCon -> BoolSource
Return whether there are any argument types for this DataCon
s original source type
isNullaryRepDataCon :: DataCon -> BoolSource
Return whether there are any argument types for this DataCon
s runtime representation type
isTupleCon :: DataCon -> BoolSource
isVanillaDataCon :: DataCon -> BoolSource
Vanilla DataCon
s are those that are nice boring Haskell 98 constructors
classDataCon :: Class -> DataConSource
dataConCannotMatch :: [Type] -> DataCon -> BoolSource
Splitting product types
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])Source
As splitProductType_maybe
, but panics if the Type
is not a product type
deepSplitProductType :: String -> Type -> (TyCon, [Type], DataCon, [Type])Source
As deepSplitProductType_maybe
, but panics if the Type
is not a product type
deepSplitProductType_maybe :: Type -> Maybe (TyCon, [Type], DataCon, [Type])Source
As splitProductType_maybe
, but in turn instantiates the TyCon
returned
and hence recursively tries to unpack it as far as it able to