Main data types

A data constructor

Type of the tags associated with each constructor possibility

Build a new data constructor

Tags are allocated from here for real constructors

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

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

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

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

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

The tag used for ordering DataCons

The type constructor that we are building via this data constructor

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.

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.

The universally-quantified type variables of the constructor

The existentially-quantified type variables of the constructor

Both the universal and existentiatial type variables of the constructor

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

The *full* constraints on the constructor type

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

 data Eq a => T a = ...

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

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

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

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

The labels for the fields of this particular DataCon

Extract the type for any given labelled field of the DataCon

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

Source-level arity of the data constructor

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

The number of fields in the representation of the constructor AFTER taking into account the unpacking of any unboxed tuple fields

Should the DataCon be presented infix?

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

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)

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)

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

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

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

All type constructors used in the definition of this type constructor, recursively. This is used to find out all the type constructors whose data constructors need to be in scope to be allowed to safely coerce under this type constructor in Safe Haskell mode.

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

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

Vanilla DataCons are those that are nice boring Haskell 98 constructors