 data TyCon
 type FieldLabel = Name
 data AlgTyConRhs
 visibleDataCons :: AlgTyConRhs > [DataCon]
 data TyConParent
 isNoParent :: TyConParent > Bool
 data SynTyConRhs
 data CoTyConDesc
 mkAlgTyCon :: Name > Kind > [TyVar] > [PredType] > AlgTyConRhs > TyConParent > RecFlag > Bool > Bool > TyCon
 mkClassTyCon :: Name > Kind > [TyVar] > AlgTyConRhs > Class > RecFlag > TyCon
 mkFunTyCon :: Name > Kind > TyCon
 mkPrimTyCon :: Name > Kind > Arity > PrimRep > TyCon
 mkKindTyCon :: Name > Kind > TyCon
 mkLiftedPrimTyCon :: Name > Kind > Arity > PrimRep > TyCon
 mkTupleTyCon :: Name > Kind > Arity > [TyVar] > DataCon > Boxity > Bool > TyCon
 mkSynTyCon :: Name > Kind > [TyVar] > SynTyConRhs > TyConParent > TyCon
 mkSuperKindTyCon :: Name > TyCon
 mkCoercionTyCon :: Name > Arity > CoTyConDesc > TyCon
 mkForeignTyCon :: Name > Maybe FastString > Kind > Arity > TyCon
 mkAnyTyCon :: Name > Kind > TyCon
 isAlgTyCon :: TyCon > Bool
 isClassTyCon :: TyCon > Bool
 isFamInstTyCon :: TyCon > Bool
 isFunTyCon :: TyCon > Bool
 isPrimTyCon :: TyCon > Bool
 isTupleTyCon :: TyCon > Bool
 isUnboxedTupleTyCon :: TyCon > Bool
 isBoxedTupleTyCon :: TyCon > Bool
 isSynTyCon :: TyCon > Bool
 isClosedSynTyCon :: TyCon > Bool
 isSuperKindTyCon :: TyCon > Bool
 isDecomposableTyCon :: TyCon > Bool
 isCoercionTyCon :: TyCon > Bool
 isCoercionTyCon_maybe :: TyCon > Maybe (Arity, CoTyConDesc)
 isForeignTyCon :: TyCon > Bool
 isAnyTyCon :: TyCon > Bool
 tyConHasKind :: TyCon > Bool
 isInjectiveTyCon :: TyCon > Bool
 isDataTyCon :: TyCon > Bool
 isProductTyCon :: TyCon > Bool
 isEnumerationTyCon :: TyCon > Bool
 isNewTyCon :: TyCon > Bool
 isAbstractTyCon :: TyCon > Bool
 isFamilyTyCon :: TyCon > Bool
 isSynFamilyTyCon :: TyCon > Bool
 isDataFamilyTyCon :: TyCon > Bool
 isUnLiftedTyCon :: TyCon > Bool
 isGadtSyntaxTyCon :: TyCon > Bool
 isTyConAssoc :: TyCon > Bool
 isRecursiveTyCon :: TyCon > Bool
 isHiBootTyCon :: TyCon > Bool
 isImplicitTyCon :: TyCon > Bool
 tyConHasGenerics :: TyCon > Bool
 tyConName :: TyCon > Name
 tyConKind :: TyCon > Kind
 tyConUnique :: TyCon > Unique
 tyConTyVars :: TyCon > [TyVar]
 tyConDataCons :: TyCon > [DataCon]
 tyConDataCons_maybe :: TyCon > Maybe [DataCon]
 tyConSingleDataCon_maybe :: TyCon > Maybe DataCon
 tyConFamilySize :: TyCon > Int
 tyConStupidTheta :: TyCon > [PredType]
 tyConArity :: TyCon > Arity
 tyConParent :: TyCon > TyConParent
 tyConClass_maybe :: TyCon > Maybe Class
 tyConFamInst_maybe :: TyCon > Maybe (TyCon, [Type])
 tyConFamilyCoercion_maybe :: TyCon > Maybe TyCon
 tyConFamInstSig_maybe :: TyCon > Maybe (TyCon, [Type], TyCon)
 synTyConDefn :: TyCon > ([TyVar], Type)
 synTyConRhs :: TyCon > SynTyConRhs
 synTyConType :: TyCon > Type
 tyConExtName :: TyCon > Maybe FastString
 algTyConRhs :: TyCon > AlgTyConRhs
 newTyConRhs :: TyCon > ([TyVar], Type)
 newTyConEtadRhs :: TyCon > ([TyVar], Type)
 unwrapNewTyCon_maybe :: TyCon > Maybe ([TyVar], Type, Maybe TyCon)
 tupleTyConBoxity :: TyCon > Boxity
 tcExpandTyCon_maybe :: TyCon > [Type] > Maybe ([(TyVar, Type)], Type, [Type])
 coreExpandTyCon_maybe :: TyCon > [Type] > Maybe ([(TyVar, Type)], Type, [Type])
 makeTyConAbstract :: TyCon > TyCon
 newTyConCo_maybe :: TyCon > Maybe TyCon
 data PrimRep
 tyConPrimRep :: TyCon > PrimRep
 primRepSizeW :: PrimRep > Int
Main TyCon data types
TyCons represent type constructors. Type constructors are introduced by things such as:
1) Data declarations: data Foo = ...
creates the Foo
type constructor of kind *
2) Type synonyms: type Foo = ...
creates the Foo
type constructor
3) Newtypes: newtype Foo a = MkFoo ...
creates the Foo
type constructor of kind * > *
4) Class declarations: class Foo where
creates the Foo
type constructor of kind *
5) Type coercions! This is because we represent a coercion from t1
to t2
as a Type
, where that type has kind t1 ~ t2
. See Coercion for more on this
This data type also encodes a number of primitive, built in type constructors such as those for function and tuple types.
type FieldLabel = NameSource
Names of the fields in an algebraic record type
data AlgTyConRhs Source
Represents righthandsides of TyCon
s for algebraic types
AbstractTyCon  Says that we know nothing about this data type, except that it's represented by a pointer. Used when we export a data type abstractly into an .hi file. 
DataFamilyTyCon  Represents an open type family without a fixed right hand side. Additional instances can appear at any time. These are introduced by either a top level declaration: data T a :: * Or an associated data type declaration, within a class declaration: class C a b where data T b :: * 
DataTyCon  Information about those 
 
NewTyCon  Information about those 

visibleDataCons :: AlgTyConRhs > [DataCon]Source
Extract those DataCon
s that we are able to learn about. Note
that visibility in this sense does not correspond to visibility in
the context of any particular user program!
Both type classes as well as family instances imply implicit
type constructors. These implicit type constructors refer to their parent
structure (ie, the class or family from which they derive) using a type of
the following form. We use TyConParent
for both algebraic and synonym
types, but the variant ClassTyCon
will only be used by algebraic TyCon
s.
data TyConParent Source
NoParentTyCon  An ordinary type constructor has no parent. 
ClassTyCon Class  Type constructors representing a class dictionary. 
AssocFamilyTyCon Class  An *associated* type of a class. 
FamInstTyCon TyCon [Type] TyCon  Type constructors representing an instance of a type family. Parameters: 1) The type family in question 2) Instance types; free variables are the 3) A 
isNoParent :: TyConParent > BoolSource
data SynTyConRhs Source
Information pertaining to the expansion of a type synonym (type
)
SynonymTyCon Type  An ordinary type synonyn. 
SynFamilyTyCon  A type synonym family e.g. 
Constructing TyCons
:: Name  
> Kind  Kind of the resulting 
> [TyVar] 

> [PredType]  Stupid theta: see 
> AlgTyConRhs  Information about dat aconstructors 
> TyConParent  
> RecFlag  Is the 
> Bool  Does it have generic functions? See 
> Bool  Was the 
> TyCon 
This is the making of an algebraic TyCon
. Notably, you have to
pass in the generic (in the XGenerics sense) information about the
type constructor  you can get hold of it easily (see Generics
module)
mkClassTyCon :: Name > Kind > [TyVar] > AlgTyConRhs > Class > RecFlag > TyConSource
Simpler specialization of mkAlgTyCon
for classes
mkFunTyCon :: Name > Kind > TyConSource
Given the name of the function type constructor and it's kind, create the
corresponding TyCon
. It is reccomended to use TypeRep.funTyCon
if you want
this functionality
mkPrimTyCon :: Name > Kind > Arity > PrimRep > TyConSource
Create an unlifted primitive TyCon
, such as Int#
mkKindTyCon :: Name > Kind > TyConSource
Kind constructors
mkLiftedPrimTyCon :: Name > Kind > Arity > PrimRep > TyConSource
Create a lifted primitive TyCon
such as RealWorld
:: Name  
> Kind  Kind of the resulting 
> Arity  Arity of the tuple 
> [TyVar] 

> DataCon  
> Boxity  Whether the tuple is boxed or unboxed 
> Bool  Does it have generic functions? See 
> TyCon 
Foreignimported (.NET) type constructors are represented
as primitive, but lifted, TyCons
for now. They are lifted
because the Haskell type T
representing the (foreign) .NET
type T
is actually implemented (in ILX) as a thunkT
mkSynTyCon :: Name > Kind > [TyVar] > SynTyConRhs > TyConParent > TyConSource
Create a type synonym TyCon
mkSuperKindTyCon :: Name > TyConSource
Create a superkind TyCon
mkCoercionTyCon :: Name > Arity > CoTyConDesc > TyConSource
Create a coercion TyCon
mkAnyTyCon :: Name > Kind > TyConSource
Predicates on TyCons
isAlgTyCon :: TyCon > BoolSource
Returns True
if the supplied TyCon
resulted from either a
data
or newtype
declaration
isClassTyCon :: TyCon > BoolSource
Is this TyCon
that for a class instance?
isFamInstTyCon :: TyCon > BoolSource
Is this TyCon
that for a family instance, be that for a synonym or an
algebraic family instance?
isFunTyCon :: TyCon > BoolSource
isPrimTyCon :: TyCon > BoolSource
Does this TyCon
represent something that cannot be defined in Haskell?
isTupleTyCon :: TyCon > BoolSource
Does this TyCon
represent a tuple?
NB: when compiling Data.Tuple
, the tycons won't reply True
to
isTupleTyCon
, becuase they are built as AlgTyCons
. However they
get spat into the interface file as tuple tycons, so I don't think
it matters.
isUnboxedTupleTyCon :: TyCon > BoolSource
Is this the TyCon
for an unboxed tuple?
isBoxedTupleTyCon :: TyCon > BoolSource
Is this the TyCon
for a boxed tuple?
isSynTyCon :: TyCon > BoolSource
isClosedSynTyCon :: TyCon > BoolSource
Is this a synonym TyCon
that can have no further instances appear?
isSuperKindTyCon :: TyCon > BoolSource
Is this a superkind TyCon
?
isCoercionTyCon :: TyCon > BoolSource
Is this a TyCon
that represents a coercion?
isForeignTyCon :: TyCon > BoolSource
Is this the TyCon
of a foreignimported type constructor?
isAnyTyCon :: TyCon > BoolSource
Is this an AnyTyCon?
tyConHasKind :: TyCon > BoolSource
isInjectiveTyCon :: TyCon > BoolSource
Injective TyCon
s can be decomposed, so that
T ty1 ~ T ty2 => ty1 ~ ty2
isDataTyCon :: TyCon > BoolSource
Returns True
for data types that are definitely represented by
heapallocated constructors. These are scrutinised by Corelevel
case
expressions, and they get info tables allocated for them.
Generally, the function will be true for all data
types and false
for newtype
s, unboxed tuples and type family TyCon
s. But it is
not guarenteed to return True
in all cases that it could.
NB: for a data type family, only the instance TyCon
s
get an info table. The family declaration TyCon
does not
isProductTyCon :: TyCon > BoolSource
isEnumerationTyCon :: TyCon > BoolSource
Is this an algebraic TyCon
which is just an enumeration of values?
isNewTyCon :: TyCon > BoolSource
Is this TyCon
that for a newtype
isAbstractTyCon :: TyCon > BoolSource
Test if the TyCon
is algebraic but abstract (invisible data constructors)
isFamilyTyCon :: TyCon > BoolSource
Is this a TyCon
, synonym or otherwise, that may have further instances appear?
isSynFamilyTyCon :: TyCon > BoolSource
Is this a synonym TyCon
that can have may have further instances appear?
isDataFamilyTyCon :: TyCon > BoolSource
Is this a synonym TyCon
that can have may have further instances appear?
isUnLiftedTyCon :: TyCon > BoolSource
isGadtSyntaxTyCon :: TyCon > BoolSource
Is this an algebraic TyCon
declared with the GADT syntax?
isTyConAssoc :: TyCon > BoolSource
isRecursiveTyCon :: TyCon > BoolSource
Is this a recursive TyCon
?
isHiBootTyCon :: TyCon > BoolSource
Did this TyCon
originate from typechecking a .h*boot file?
isImplicitTyCon :: TyCon > BoolSource
Identifies implicit tycons that, in particular, do not go into interface files (because they are implicitly reconstructed when the interface is read).
Note that:
 Associated families are implicit, as they are reconstructed from the class declaration in which they reside, and
 Family instances are not implicit as they represent the instance body
(similar to a
dfun
does that for a class instance).
tyConHasGenerics :: TyCon > BoolSource
Does this TyCon
have any generic to/from functions available? See also hasGenerics
Extracting information out of TyCons
tyConUnique :: TyCon > UniqueSource
tyConTyVars :: TyCon > [TyVar]Source
tyConDataCons :: TyCon > [DataCon]Source
As tyConDataCons_maybe
, but returns the empty list of constructors if no constructors
could be found
tyConDataCons_maybe :: TyCon > Maybe [DataCon]Source
tyConSingleDataCon_maybe :: TyCon > Maybe DataConSource
If the given TyCon
has a single data constructor, i.e. it is a data
type with one
alternative, a tuple type or a newtype
then that constructor is returned. If the TyCon
has more than one constructor, or represents a primitive or function type constructor then
Nothing
is returned. In any other case, the function panics
tyConFamilySize :: TyCon > IntSource
tyConStupidTheta :: TyCon > [PredType]Source
Find the "stupid theta" of the TyCon
. A "stupid theta" is the context to the left of
an algebraic type declaration, e.g. Eq a
in the declaration data Eq a => T a ...
tyConArity :: TyCon > AritySource
tyConClass_maybe :: TyCon > Maybe ClassSource
If this TyCon
is that for a class instance, return the class it is for.
Otherwise returns Nothing
tyConFamInst_maybe :: TyCon > Maybe (TyCon, [Type])Source
If this TyCon
is that of a family instance, return the family in question
and the instance types. Otherwise, return Nothing
synTyConDefn :: TyCon > ([TyVar], Type)Source
synTyConRhs :: TyCon > SynTyConRhsSource
Extract the information pertaining to the right hand side of a type synonym (type
) declaration. Panics
if the given TyCon
is not a type synonym
synTyConType :: TyCon > TypeSource
tyConExtName :: TyCon > Maybe FastStringSource
Just e
for foreignimported types,
holds the name of the imported thing
algTyConRhs :: TyCon > AlgTyConRhsSource
Extract an AlgTyConRhs
with information about data constructors from an algebraic or tuple
TyCon
. Panics for any other sort of TyCon
newTyConRhs :: TyCon > ([TyVar], Type)Source
newTyConEtadRhs :: TyCon > ([TyVar], Type)Source
tupleTyConBoxity :: TyCon > BoxitySource
Extract the boxity of the given TyCon
, if it is a TupleTyCon
.
Panics otherwise
Manipulating TyCons
:: TyCon  
> [Type]  Arguments to 
> Maybe ([(TyVar, Type)], Type, [Type])  Returns a 
Used to create the view the typechecker has on TyCon
s. We expand (closed) synonyms only, cf. coreExpandTyCon_maybe
Used to create the view Core has on TyCon
s. We expand not only closed synonyms like tcExpandTyCon_maybe
,
but also nonrecursive newtype
s
Primitive representations of Types
A PrimRep
is an abstraction of a type. It contains information that
the code generator needs in order to pass arguments, return results,
and store values of this type.
tyConPrimRep :: TyCon > PrimRepSource
Find the primitive representation of a TyCon
primRepSizeW :: PrimRep > IntSource
Find the size of a PrimRep
, in words