Safe Haskell	None
Language	Haskell98

Foreign.JavaScript

Contents

Synopsis
Server
JavaScript FFI

Synopsis

A JavaScript foreign function interface (FFI).

This module implements a web server that communicates with a web browser and allows you to execute arbitrary JavaScript code on it.

NOTE: This module is used internally by the Graphics.UI.Threepenny library, but the types are not compatible directly (although some escape hatches are provided). Use Foreign.JavaScript only if you want to roll your own interface to the web browser.

Server

serve #

Arguments

:: Config	Configuration options.
-> (Window -> IO ())	Initialization whenever a client connects.
-> IO ()

Run a Foreign.JavaScript server.

defaultConfig :: Config #

Default configuration.

Port from environment variable or 8023, listening on localhost, no custom HTML, no static directory, logging to stderr, do reload on disconnect, buffer FFI calls.

data Config #

Static configuration for a Foreign.JavaScript server.

This is a record type which has the following fields:

```
jsPort :: Maybe Int
```
Port number. Nothing means that the port number is read from the environment variable PORT. Alternatively, port 8023 is used if this variable is not set.
```
jsAddr :: Maybe ByteString
```
Bind address. Nothing means that the bind address is read from the environment variable ADDR. Alternatively, address 127.0.0.1 is used if this variable is not set.
```
jsCustomHTML :: Maybe FilePath
```
Custom HTML file to replace the default one.
```
jsStatic :: Maybe FilePath
```
Directory that is served under /static.
```
jsLog :: ByteString -> IO ()
```
Function to print a single log message.
```
jsWindowReloadOnDisconnect :: Bool
```
Reload the browser window if the connection to the server was dropped accidentally, for instance because the computer was put to sleep and awoken again.
```
jsCallBufferMode :: CallBufferMode
```
The initial CallBufferMode to use for runFunction. It can be changed at any time with setCallBufferMode.

(For reasons of forward compatibility, the constructor is not exported.)

data Server #

Representation of a Foreign.JavaScript server.

Can be used for dynamic configuration, e.g. serving additional files.

type MimeType = String #

MIME type.

type URI = String #

URI type.

FIXME: Use the correct type from Network.URI

loadFile :: Server -> MimeType -> FilePath -> IO String #

Begin to serve a local file with a given MimeType under a URI.

loadDirectory :: Server -> FilePath -> IO String #

Begin to serve a local directory under a URI.

data Window #

Representation of a browser window.

getServer :: Window -> Server #

Server that the browser window communicates with.

getCookies :: Window -> [Cookie] #

Cookies that the browser window has sent to the server when connecting.

root :: Window -> RemotePtr () #

For the purpose of controlling garbage collection, every Window as an associated RemotePtr that is alive as long as the external JavaScript connection is alive.

JavaScript FFI

class ToJS a where #

Helper class for rendering Haskell values as JavaScript expressions.

Minimal complete definition

render

Methods

render :: a -> IO JSCode #

renderList :: [a] -> IO JSCode #

Instances

ToJS Bool #
Methods render :: Bool -> IO JSCode # renderList :: [Bool] -> IO JSCode #
ToJS Char #
Methods render :: Char -> IO JSCode # renderList :: [Char] -> IO JSCode #
ToJS Double #
Methods render :: Double -> IO JSCode # renderList :: [Double] -> IO JSCode #
ToJS Float #
Methods render :: Float -> IO JSCode # renderList :: [Float] -> IO JSCode #
ToJS Int #
Methods render :: Int -> IO JSCode # renderList :: [Int] -> IO JSCode #
ToJS Text #
Methods render :: Text -> IO JSCode # renderList :: [Text] -> IO JSCode #
ToJS Value #
Methods render :: Value -> IO JSCode # renderList :: [Value] -> IO JSCode #
ToJS JSObject #
Methods render :: JSObject -> IO JSCode # renderList :: [JSObject] -> IO JSCode #
ToJS Element #
Methods render :: Element -> IO JSCode # renderList :: [Element] -> IO JSCode #
ToJS a => ToJS [a] #
Methods render :: [a] -> IO JSCode # renderList :: [[a]] -> IO JSCode #

class FromJS a #

Helper class for converting JavaScript values to Haskell values.

Minimal complete definition

fromJS

Instances

FromJS Double #
Methods fromJS :: FromJS' Double
FromJS Float #
Methods fromJS :: FromJS' Float
FromJS Int #
Methods fromJS :: FromJS' Int
FromJS () #
Methods fromJS :: FromJS' ()
FromJS String #
Methods fromJS :: FromJS' String
FromJS Text #
Methods fromJS :: FromJS' Text
FromJS Value #
Methods fromJS :: FromJS' Value
FromJS NewJSObject #
Methods fromJS :: FromJS' NewJSObject
FromJS JSObject #
Methods fromJS :: FromJS' JSObject
FromJS [JSObject] #
Methods fromJS :: FromJS' [JSObject]

data JSFunction a #

A JavaScript function with a given output type a.

Instances

Functor JSFunction #	Change the output type of a `JSFunction`.
Methods fmap :: (a -> b) -> JSFunction a -> JSFunction b # (<$) :: a -> JSFunction b -> JSFunction a #
FromJS b => FFI (JSFunction b) #
Methods fancy :: ([JSCode] -> IO JSCode) -> JSFunction b

type JSObject = RemotePtr JSPtr #

A mutable JavaScript object.

data JavaScriptException #

Instances

Show JavaScriptException #
Methods showsPrec :: Int -> JavaScriptException -> ShowS # show :: JavaScriptException -> String # showList :: [JavaScriptException] -> ShowS #
Exception JavaScriptException #
Methods toException :: JavaScriptException -> SomeException # fromException :: SomeException -> Maybe JavaScriptException # displayException :: JavaScriptException -> String #

class FFI a #

Helper class for making ffi a variable argument function.

Minimal complete definition

fancy

Instances

FromJS b => FFI (JSFunction b) #
Methods fancy :: ([JSCode] -> IO JSCode) -> JSFunction b
(ToJS a, FFI b) => FFI (a -> b) #
Methods fancy :: ([JSCode] -> IO JSCode) -> a -> b

ffi :: FFI a => String -> a #

Simple JavaScript FFI with string substitution.

Inspired by the Fay language. https://github.com/faylang/fay/wiki

example :: String -> Int -> JSFunction String
example = ffi "$(%1).prop('checked',%2)"

The ffi function takes a string argument representing the JavaScript code to be executed on the client. Occurrences of the substrings %1 to %9 will be replaced by subequent arguments. The substring %% in the original will be replaced by % (character escape).

Note: Always specify a type signature! The types automate how values are marshalled between Haskell and JavaScript. The class instances for the FFI class show which conversions are supported.

runFunction :: Window -> JSFunction () -> IO () #

Run a JavaScript function, but do not wait for a result.

NOTE: The JavaScript function need not be executed immediately, it can be buffered and sent to the browser window at a later time. See setCallBufferMode and flushCallBuffer for more.

callFunction :: Window -> JSFunction a -> IO a #

Call a JavaScript function and wait for the result.

data NewJSObject #

A mutable JavaScript object that has just been created. This a dummy type used for additional type safety.

Instances

FromJS NewJSObject #
Methods fromJS :: FromJS' NewJSObject

unsafeCreateJSObject :: Window -> JSFunction NewJSObject -> IO JSObject #

Run a JavaScript function that creates a new object. Return a corresponding JSObject without waiting for the browser to send a result.

WARNING: This function assumes that the supplied JavaScript code does, in fact, create an object that is new.

data CallBufferMode #

Specification of how JavaScript functions should be called.

Constructors

NoBuffering	When `runFunction` is used to call a JavaScript function, immediately send a message to the browser window to execute said function.
BufferRun	When `runFunction` is used to call a JavaScript function, hold back any message to the server. All JavaScript functions that are held back in this way are combined into a single message, which is finally sent whenever `callFunction` or `flushCallBuffer` are used, or an exported Haskell function is called.
FlushOften	The same as `BufferRun`, but this mode indicates client libraries and programs are encouraged to flush the buffer more often to simplify usage. Users may choose `BufferRun` instead if they want more control over flushing the buffer.
FlushPeriodically	The same as `BufferRun`, except that the buffer will also be flushed every 300ms.

setCallBufferMode :: Window -> CallBufferMode -> IO () #

Set the call buffering mode for the given browser window.

getCallBufferMode :: Window -> IO CallBufferMode #

Get the call buffering mode for the given browser window.

flushCallBuffer :: Window -> IO () #

Flush the call buffer, i.e. send all outstanding JavaScript to the client in one single message.

class IsHandler a #

Helper class for exporting Haskell functions to JavaScript as event handlers.

Minimal complete definition

convertArgs, handle

Instances

IsHandler (IO ()) #
Methods convertArgs :: IO () -> Int -> [JSCode] handle :: IO () -> Window -> [Value] -> IO ()
(FromJS a, IsHandler b) => IsHandler (a -> b) #
Methods convertArgs :: (a -> b) -> Int -> [JSCode] handle :: (a -> b) -> Window -> [Value] -> IO ()

exportHandler :: IsHandler a => Window -> a -> IO JSObject #

Export a Haskell function as an event handler.

The result is a JavaScript Function object that can be called from JavaScript like a regular function. However, the corresponding Haskell function will not be run immediately, rather it will be added to the event queue and processed like an event. In other words, this the Haskell code is only called asynchronously.

WARNING: The event handler will be garbage collected unless you keep a reference to it on the Haskell side! Registering it with a JavaScript function will generally not keep it alive.

onDisconnect :: Window -> IO () -> IO () #

Register an action to be performed when the client disconnects.

debug :: Window -> String -> IO () #

Send a debug message to the JavaScript console.

timestamp :: Window -> IO () #

Print a timestamp and the time difference to the previous one in the JavaScript console.