send a remote monad for execution on a JavaScript engine. The monad may be split into several packets for transmission and exection.

send an (applicative) Packet. This packet always sent atomically to JavaScript.

send with all JavaScript exceptions caught and returned.

command statement to execute in JavaScript. ';' is not needed as a terminator. Should never throw an exception, which may be reported to console.log.

procedure expression to execute in JavaScript. ';' is not needed as a terminator. Should never throw an exception, but any exceptions are returned to the send as Haskell exceptions.

Procedures can return Promises. Before completing the transaction, all the values for all the procedures that are promises are fulfilled (using Promises.all).

If a procedure throws an exception, future commands and procedures in the same packet will not be executed. Use promises to allow all commands and procedures to be invoked, if needed.

constructor expression to execute in JavaScript. ';' is not needed as a terminator. Should never throw an exception, but any exceptions are returned to the send as Haskell exceptions.

The value returned in not returned to Haskell. Instead, a handle is returned, that can be used to access the remote value. Examples of remote values include objects that can not be serialized, or values that are too large to serialize.

The first type argument is the phantom type of the RemoteValue, so that type application can be used to specify the type.

The Remote Applicative Packet

The Remote Monad

delete a remote value.

localize brings a remote value into Haskell.

remote sends a local value to JavaScript.

generate the text for a RemoteValue. They can be used as assignment targets as well, but exposes the JavaScript scoping semantics.

Generate a JavaScript value, including for RemoteValue's.

Generate a function call

Generate JavaScript number

Generate (quoted) JavaScript string

Send an event back to Haskell

Add a listener for events. There can be many. non-blocking.

From JavaScript, you can call event(..) to send values to this listener. Any valid JSON value can be sent.

listen for the next event. blocking.

From JavaScript, you can call event(..) to send values to this listener. Any valid JSON value can be sent.

readEventChan uses STM to read the next event.

From JavaScript, you can call event(..) to send values to this channel. Any valid JSON value can be sent.

This accepts WebSocket requests, calls the callback with an Engine that can be used to access JavaScript.

An Engine is a handle to a specific JavaScript engine

The WAI application.

Note that, since WAI 3.0, this type is structured in continuation passing style to allow for proper safe resource handling. This was handled in the past via other means (e.g., ResourceT). As a demonstration:

app :: Application
app req respond = bracket_
    (putStrLn "Allocating scarce resource")
    (putStrLn "Cleaning up")
    (respond $ responseLBS status200 [] "Hello World")