Documentation

Type synonym for a "tell-style" query - queries that only cause effects, | but that cannot receive a return value. | | In a query algebra, a tell constructor carries the algebra's type variable | as its last argument. For example: | | ``` purescript | data Query a | = SomeTell a | | SomeOtherTell String a | | NotATell (Boolean -> a) | ``` | | Both SomeTell and SomeOtherTell carry a plain a as a value, whereas | NotATell has a as the result of a function so is considered to be a | "request" (see below).

Takes a data constructor of query algebra f and creates a tell query. | | For example: | | ```purescript | data Query a = Tick a | | sendTick :: forall o. H.HalogenSocket Query o IO -> IO (Maybe ()) | sendTick app = app.query (H.mkTell Tick) | ```

Type synonym for an "request-style" query - queries that can cause effects | as well as fetching some information from a component. | | In a query algebra, a request constructor carries the algebra's type | variable as the return value of a function as its last argument. For | example: | | ``` purescript | data Query a = SomeRequest (Boolean -> a) | ```

Takes a data constructor of query algebra f and creates a request query. | | For example: | | ```purescript | data Query a = GetTickCount (Int -> a) | | getTickCount :: forall o. H.HalogenSocket Query o IO -> IO (Maybe Int) | getTickCount app = app.query (H.mkRequest GetTickCount) | ```

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

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.

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

Joins a forked process. Attempting to join a forked process that has | already ended will result in eval continuing immediately. Attempting | to join a forked process that has been killed will also terminate the | current eval.

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

Sends a query to a child of a component at the specified slot.

Sends a query to all children of a component at a given slot label.

Raises an output message for the component.

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.

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.

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