Language.GraphQL.Type.Out

Output types and values, monad transformer stack used by the GraphQL resolvers.

This module is intended to be imported qualified, to avoid name clashes with In.

Documentation

data Context

Resolution context holds resolver arguments and the root value.

Constructors

Context

Fields

• arguments :: Arguments
• values :: Value

data Field m

Output object field definition.

Constructors

Field

Fields

• (Maybe Text)

  Description.

• (Type m)

  Field type.

• Arguments

  Arguments.

data InterfaceType m

Interface Type Definition.

When a field can return one of a heterogeneous set of types, a Interface type is used to describe what types are possible, and what fields are in common across all types.

Constructors

InterfaceType Name (Maybe Text) [InterfaceType m] (HashMap Name (Field m))

Instances

Eq (InterfaceType a)

Defined in Language.GraphQL.Type.Out

Methods

(==) :: InterfaceType a -> InterfaceType a -> Bool

(/=) :: InterfaceType a -> InterfaceType a -> Bool

Show (InterfaceType a)

Defined in Language.GraphQL.Type.Out

Methods

showsPrec :: Int -> InterfaceType a -> ShowS

show :: InterfaceType a -> String

showList :: [InterfaceType a] -> ShowS

data ObjectType m

Object type definition.

Almost all of the GraphQL types you define will be object types. Object types have a name, but most importantly describe their fields.

Constructors

ObjectType Name (Maybe Text) [InterfaceType m] (HashMap Name (Resolver m))

Instances

Eq (ObjectType a)

Defined in Language.GraphQL.Type.Out

Methods

(==) :: ObjectType a -> ObjectType a -> Bool

(/=) :: ObjectType a -> ObjectType a -> Bool

Show (ObjectType a)

Defined in Language.GraphQL.Type.Out

Methods

showsPrec :: Int -> ObjectType a -> ShowS

show :: ObjectType a -> String

showList :: [ObjectType a] -> ShowS

type Resolve m = ReaderT Context m Value

Monad transformer stack used by the resolvers for determining the resolved value of a field.

type Subscribe m = ReaderT Context m (SourceEventStream m)

Monad transformer stack used by the resolvers for determining the resolved event stream of a subscription field.

data Resolver m

Resolver associates some function(s) with each Field. ValueResolver resolves a Field into a Value. EventStreamResolver resolves additionally a Field into a SourceEventStream if it is the field of a root subscription type.

The resolvers aren't part of the Field itself because not all fields have resolvers (interface fields don't have an implementation).

Constructors

ValueResolver (Field m) (Resolve m)

EventStreamResolver (Field m) (Resolve m) (Subscribe m)

type SourceEventStream m = ConduitT () Value m ()

A source stream represents the sequence of events, each of which will trigger a GraphQL execution corresponding to that event.

data Type m

These types may be used as output types as the result of fields.

GraphQL distinguishes between "wrapping" and "named" types. Each wrapping type can wrap other wrapping or named types. Wrapping types are lists and Non-Null types (named types are nullable by default).

Constructors

NamedScalarType ScalarType

NamedEnumType EnumType

NamedObjectType (ObjectType m)

NamedInterfaceType (InterfaceType m)

NamedUnionType (UnionType m)

ListType (Type m)

NonNullScalarType ScalarType

NonNullEnumType EnumType

NonNullObjectType (ObjectType m)

NonNullInterfaceType (InterfaceType m)

NonNullUnionType (UnionType m)

NonNullListType (Type m)

Instances

Eq (Type m)

Defined in Language.GraphQL.Type.Out

Methods

(==) :: Type m -> Type m -> Bool

(/=) :: Type m -> Type m -> Bool

Show (Type a)

Defined in Language.GraphQL.Type.Out

Methods

showsPrec :: Int -> Type a -> ShowS

show :: Type a -> String

showList :: [Type a] -> ShowS

data UnionType m

Union Type Definition.

When a field can return one of a heterogeneous set of types, a Union type is used to describe what types are possible.

Constructors

UnionType Name (Maybe Text) [ObjectType m]

Instances

Eq (UnionType a)

Defined in Language.GraphQL.Type.Out

Methods

(==) :: UnionType a -> UnionType a -> Bool

(/=) :: UnionType a -> UnionType a -> Bool

Show (UnionType a)

Defined in Language.GraphQL.Type.Out

Methods

showsPrec :: Int -> UnionType a -> ShowS

show :: UnionType a -> String

showList :: [UnionType a] -> ShowS

argument :: Monad m => Name -> Resolve m

Retrieves an argument by its name. If the argument with this name couldn't be found, returns Null (i.e. the argument is assumed to be optional then).

isNonNullType :: forall m. Type m -> Bool

Checks whether the given output type is a non-null type.

pattern EnumBaseType :: forall m. EnumType -> Type m

Matches either NamedEnumType or NonNullEnumType.

pattern InterfaceBaseType :: forall m. InterfaceType m -> Type m

Matches either NamedInterfaceType or NonNullInterfaceType.

pattern ListBaseType :: forall m. Type m -> Type m

Matches either ListType or NonNullListType.

pattern ObjectBaseType :: forall m. ObjectType m -> Type m

Matches either NamedObjectType or NonNullObjectType.

pattern ScalarBaseType :: forall m. ScalarType -> Type m

Matches either NamedScalarType or NonNullScalarType.

pattern UnionBaseType :: forall m. UnionType m -> Type m

Matches either NamedUnionType or NonNullUnionType.