AJAX

client-side half of a typed AJAX communication channel.

To use this library, you could start by defining a type in a file that can be shared between the Haskell Server and Fay client. For example:

    data Command
        = SendGuess Guess (ResponseType (Maybe Row))
        | FetchBoard (ResponseType (Maybe Board))
        deriving (Read, Show, Data, Typeable)
    instance Foreign Command

The ResponseType argument specifies what type each command should return. Using GADTs would be cleaner, but Fay does not support GADTs yet.

To execute a remote function we use the call function:

      call /ajax FetchBoard $ mboard -> ...

Due to the single-threaded nature of Javascript, we do not want to block until the call returns a value, so we perform the AJAX request asynchronously. The third argument to call is the callback function to run when the response is received.

Documentation

call

Arguments

:: String

URL to POST AJAX request to

-> (ResponseType res -> cmd)

AJAX command to send to server

-> (res -> Fay ())

callback function to handle response

-> Fay ()

Asynchronously call a command

Note: if the server returns 404 or some other non-success exit code, the callback function will never be run.

This function is just a wrapper around ajaxCommand which uses the 'ResponseType res' phantom-typed parameter for added type safety.

ajaxCommand :: String -> Automatic cmd -> (Automatic res -> Fay ()) -> Fay ()

Run the AJAX command. (internal)

You probably want to use call which provides additional type-safety.

Note: if the server returns 404 or some other non-success exit code, the callback function will never be run.

see also: call