Happstack.State.ComponentSystem

Documentation

data End

Equivalent of [] for type level lists. Used for Components that have no dependencies

Constructors

End

Instances

SubHandlers End

In correspondence with its role as [] in the type level list, the instance for End does not add any components to the set.

data h :+: t

Type level Cons for enumerating type dependencies of a Component

Constructors

h :+: t

Instances

(Methods a, Component a, SubHandlers b) => SubHandlers (:+: a b)

This is the instance that completes the definition of :+: and End as being the constructors of a type level list in SubHandlers. Note that since b needs to be an instance of SubHandlers, the list needs to be terminated with End.

class (Serialize ev, Serialize res) => UpdateEvent ev res | ev -> res

Instances

UpdateEvent SetCheckpointState ()

Typeable st => UpdateEvent (SetNewState st) ()

class (Serialize ev, Serialize res) => QueryEvent ev res | ev -> res

Instances

QueryEvent GetCheckpointState ByteString

Typeable st => QueryEvent (GetState st) ByteString

data Method st where

Method is the actual type that all Updates and Querys eventually get lifted into via mkMethods.

Constructors

Update :: UpdateEvent ev res => (ev -> Update st res) -> Method st

Query :: QueryEvent ev res => (ev -> Query st res) -> Method st

Instances

Show (Method st)

methodType :: Method t -> String

Displays the type of a Method

class Methods a where

Class for enumerating the set of defined methods by the type of the state. Instances should not be defined directly, but using mkMethods

Methods

methods :: Proxy a -> [Method a]

data MethodMap where

Constructors

MethodMap :: Component st => Map String (Method st) -> MethodMap

Instances

Show MethodMap

type ComponentTree = Map String MethodMap

State type -> method map

type ComponentVersions = Map String [ByteString]

State type -> all versions

class (SubHandlers (Dependencies a), Serialize a) => Component a where

In order to be used as a part of Happstack's MACID state, a data type needs to be an instance of Component. The minimal definition is an initialValue and the type corresponding to the set of Dependencies. Note that the SubHandlers condition will be automatically met if the Dependencies is built from End and :+: with other instances of Component and Methods

Associated Types

type Dependencies a

Methods

initialValue :: a

onLoad :: Proxy a -> IO ()

class SubHandlers a where

SubHandlers is used to build up the set of components corresponding to the instance type.

Methods

subHandlers :: a -> Collect ()

Instances

SubHandlers End

In correspondence with its role as [] in the type level list, the instance for End does not add any components to the set.

(Methods a, Component a, SubHandlers b) => SubHandlers (:+: a b)

This is the instance that completes the definition of :+: and End as being the constructors of a type level list in SubHandlers. Note that since b needs to be an instance of SubHandlers, the list needs to be terminated with End.

data Collection

Constructors

Collection ComponentTree ComponentVersions [IO ()]

addItem :: MonadState Collection m => String -> MethodMap -> [ByteString] -> IO () -> m ()

type Collect = State Collection

collectHandlers :: (Methods a, Component a) => Proxy a -> (ComponentTree, ComponentVersions, [IO ()])

collectHandlers' :: (Methods a, Component a) => Proxy a -> Collect ()

dup :: String -> b

An error is thrown when this is evaluated.