Language.Haskell.Syntax.Decls

A type or class declaration.

Located Declaration of a Type or Class

Type or Class Group

type class

True = argument is a data/newtype declaration.

type or type instance declaration

type/data family declaration

type family declaration

data family declaration

open type family info

closed type family info

type Family Declaration

Located type Family Declaration

Instance Declaration

Located Instance Declaration

Type Family Instance Declaration

Located Type Family Instance Declaration

Type family default declarations. A convenient synonym for TyFamInstDecl. See Note [Type family instance declarations in HsSyn].

Located type family default declarations.

Data Family Instance Declaration

Located Data Family Instance Declaration

Family Equation

One equation in a type family instance declaration, data family instance declaration, or type family default. See Note [Type family instance declarations in HsSyn] See Note [Family instance declaration binders]

Type Family Instance Equation

Located Type Family Instance Equation

HsFamEqnPats represents patterns on the left-hand side of a type instance, e.g. `type instance F k (a :: k) = a` has patterns `k` and `(a :: k)`.

HsFamEqnPats used to be called HsTyPats but it was renamed to avoid confusion with a different notion of type patterns, see #23657.

Located Class Instance Declaration

Class Instance Declaration

Stand-alone 'deriving instance' declaration

Located stand-alone 'deriving instance' declaration

Which technique the user explicitly requested when deriving an instance.

A Located DerivStrategy.

Located Rule Declarations

Rule Declarations

Rule Declaration

Located Rule Declaration

Rule Binder

Located Rule Binder

Default Declaration

Located Default Declaration

A splice can appear with various decorations wrapped around it. This data type captures explicitly how it was originally written, for use in the pretty printer.

Splice Declaration

Located Splice Declaration

Foreign Declaration

Located Foreign Declaration

data T b = forall a. Eq a => MkT a b
  MkT :: forall b a. Eq a => MkT a b

data T b where
     MkT1 :: Int -> T Int

data T = Int MkT Int
       | MkT2

data T a where
     Int MkT Int :: T Int

data Constructor Declaration

Located data Constructor Declaration

The arguments in a Haskell98-style data constructor.

The arguments in a GADT constructor. Unlike Haskell98-style constructors, GADT constructors cannot be declared with infix syntax. As a result, we do not use HsConDetails here, as InfixCon would be an unrepresentable state. (There is a notion of infix GADT constructors for the purposes of derived Show instances—see Note [Infix GADT constructors] in GHC.Tc.TyCl—but that is an orthogonal concern.)

Documentation comment Declaration

Located Documentation comment Declaration

Warning pragma Declaration

Located Warning pragma Declaration

Warning pragma Declarations

Located Warning Declarations

Annotation Declaration

Located Annotation Declaration

Annotation Provenance

Role Annotation Declaration

Located Role Annotation Declaration

type Family Result Signature

Located type Family Result Signature

If the user supplied an injectivity annotation it is represented using InjectivityAnn. At the moment this is a single injectivity condition - see Note [Injectivity annotation]. `Located name` stores the LHS of injectivity condition. `[Located name]` stores the RHS of injectivity condition. Example:

type family Foo a b c = r | r -> a c where ...

This will be represented as "InjectivityAnn r [a, c]"

Located Injectivity Annotation