Halogen.Hooks.HookM

data HookF m a

A DSL compatible with HalogenM which is used to write effectful code for Hooks.

Constructors

• Modify (StateId StateValue) (StateValue -> StateValue) (StateValue -> a)
• Subscribe (SubscriptionId -> Emitter (HookM m Unit)) (SubscriptionId -> a)
• Unsubscribe SubscriptionId a
• Lift (m a)
• ChildQuery (ChildQueryBox SlotType a)
• Raise OutputValue a
• Par (HookAp m a)
• Fork (HookM m Unit) (ForkId -> a)
• Kill ForkId a
• GetRef RefLabel (Maybe Element -> a)

Instances

• (Functor m) => Functor (HookF m)

newtype HookM m a

The Hook effect monad, used to write effectful code in Hooks functions. This monad is fully compatible with HalogenM, meaning all functionality available for HalogenM is available in HookM.

Constructors

• HookM (Free (HookF m) a)

Instances

• Functor (HookM m)
• Apply (HookM m)
• Applicative (HookM m)
• Bind (HookM m)
• Monad (HookM m)
• (Semigroup a) => Semigroup (HookM m a)
• (Monoid a) => Monoid (HookM m a)
• (MonadEffect m) => MonadEffect (HookM m)
• (MonadAff m) => MonadAff (HookM m)
• MonadTrans HookM
• MonadRec (HookM m)
• (MonadAsk r m) => MonadAsk r (HookM m)
• (MonadTell w m) => MonadTell w (HookM m)
• (MonadThrow e m) => MonadThrow e (HookM m)
• Parallel (HookAp m) (HookM m)

newtype HookAp m a

An applicative-only version of HookM to allow for parallel evaluation.

Constructors

• HookAp (FreeAp (HookM m) a)

Instances

• Newtype (HookAp m a) _
• Functor (HookAp m)
• Apply (HookAp m)
• Applicative (HookAp m)
• Parallel (HookAp m) (HookM m)

get :: forall state m. StateId state -> HookM m state

Get a piece of state using an identifier received from the useState hook.

_ /\ countId :: StateId Int <- Hooks.useState 0

let
  onClick = do
    count :: Int <- Hooks.get countId
    ...

modify_ :: forall state m. StateId state -> (state -> state) -> HookM m Unit

Modify a piece of state using an identifier received from the useState hook.

_ /\ countId :: StateId Int <- Hooks.useState 0

let
  onClick = do
    Hooks.modify_ countId (_ + 10)

modify :: forall state m. StateId state -> (state -> state) -> HookM m state

Modify a piece of state using an identifier received from the useState hook, returning the new state.

_ /\ countId :: StateId Int <- Hooks.useState 0

let
  onClick = do
    count :: Int <- Hooks.modify countId (_ + 10)
    ...

put :: forall state m. StateId state -> state -> HookM m Unit

Overwrite a piece of state using an identifier received from the useState hook.

_ /\ countId :: StateId Int <- Hooks.useState 0

let
  onClick = do
    Hooks.put countId 10

raise :: forall o m. OutputToken o -> o -> HookM m Unit

Raise an output message for the component. Requires a token carrying the output type of the component, which is provided by the Hooks.component function.

query :: forall m label ps query o' slot a _1. Cons label (Slot query o' slot) _1 ps => IsSymbol label => Ord slot => SlotToken ps -> Proxy label -> slot -> query a -> HookM m (Maybe a)

Send a query to a child of a component at the specified slot. Requires a token carrying the slot type of the component, which is provided by the Hooks.component function.

request :: forall m label ps query o' slot a _1. Cons label (Slot query o' slot) _1 ps => IsSymbol label => Ord slot => SlotToken ps -> Proxy label -> slot -> Request query a -> HookM m (Maybe a)

Send a query-request to a child of a component at the specified slot. Requires a token carrying the slot type of the component, which is provided by the Hooks.component function.

tell :: forall m label ps query o' slot _1. Cons label (Slot query o' slot) _1 ps => IsSymbol label => Ord slot => SlotToken ps -> Proxy label -> slot -> Tell query -> HookM m Unit

Send a tell-request to a child of a component at the specified slot. Requires a token carrying the slot type of the component, which is provided by the Hooks.component function.

queryAll :: forall m label ps query o' slot a _1. Cons label (Slot query o' slot) _1 ps => IsSymbol label => Ord slot => SlotToken ps -> Proxy label -> query a -> HookM m (Map slot a)

Send a query to all children of a component at the specified slot. Requires a token carrying the slot type of the component, which is provided by the Hooks.component function.

subscribe :: forall m. Emitter (HookM m Unit) -> HookM m SubscriptionId

Subscribes a component to an Emitter. When a component is disposed of any active subscriptions will automatically be stopped and no further subscriptions will be possible during finalization.

subscribe' :: forall m. (SubscriptionId -> Emitter (HookM m Unit)) -> HookM m Unit

An alternative to subscribe, intended for subscriptions that unsubscribe themselves. Instead of returning the SubscriptionId from subscribe', it is passed into an Emitter constructor. This allows emitted queries to include the SubscriptionId, rather than storing it in the state of the component.

When a component is disposed of any active subscriptions will automatically be stopped and no further subscriptions will be possible during finalization.

unsubscribe :: forall m. SubscriptionId -> HookM m Unit

Unsubscribes a component from an Emitter. If the subscription associated with the ID has already ended this will have no effect.

fork :: forall m. HookM m Unit -> HookM m ForkId

Starts a HalogenM process running independent from the current eval "thread".

A commonly use case for fork is in component initializers where some async action is started. Normally all interaction with the component will be blocked until the initializer completes, but if the async action is forked instead, the initializer can complete synchronously while the async action continues.

Some care needs to be taken when using a fork that can modify the component state, as it's easy for the forked process to "clobber" the state (overwrite some or all of it with an old value) by mistake.

When a component is disposed of any active forks will automatically be killed. New forks can be started during finalization but there will be no means of killing them.

kill :: forall m. ForkId -> HookM m Unit

Kills a forked process if it is still running. Attempting to kill a forked process that has already ended will have no effect.

getRef :: forall m. RefLabel -> HookM m (Maybe Element)

Retrieves an Element value that is associated with a Ref in the rendered o of a component. If there is no currently rendered value for the requested ref this will return Nothing.

getHTMLElementRef :: forall m. RefLabel -> HookM m (Maybe HTMLElement)

Retrieves a HTMLElement value that is associated with a Ref in the rendered o of a component. If there is no currently rendered value (or it is not an HTMLElement) for the request will return Nothing.