YOW Lambda Jam GHCJS workshop example

testFfi.hs

{-# LANGUAGE ForeignFunctionInterface, JavaScriptFFI #-}
{-# LANGUAGE OverloadedStrings #-}

module Main where

import Data.Int
import System.Timeout
import Control.Monad
import Control.Exception

import GHCJS.Types
import GHCJS.Foreign

foreign import javascript unsafe "Math.cos($1)"
  js_cos :: Double -> Double

foreign import javascript unsafe "$r1 = $1_1; $r2 = $1_2;"
  js_id :: Int64 -> Int64

foreign import javascript interruptible "setTimeout(function() { $c(123); }, 1000);"
  js_wait :: IO Int

foreign import javascript unsafe "new XMLHttpRequest()"
  js_createXHR :: IO XHR

foreign import javascript interruptible
  "$2.open('GET', $1);\
  \$2.onload = function() { $c($2.responseText); };\
  \$2.send();"
  js_sendXHR :: JSString -> XHR -> IO JSString

foreign import javascript unsafe "$1.abort();"
  js_abortXHR :: XHR -> IO ()

data XHR_
type XHR = JSRef XHR_

xhr :: JSString -> IO JSString
xhr url = do
  x <- js_createXHR
  js_sendXHR url x `onException` js_abortXHR x

fib :: Int -> Int
fib 0 = 0
fib 1 = 1
fib n = fib (n - 2) + fib (n - 1)

fib' :: Int
fib' = fib 37

main :: IO ()
main = putStrLn . fromJSString =<< xhr "/test.txt"