first demo, broken

.gitignore

@@ -1 +1,2 @@
-elm-stuff
+elm-stuff
+elm.js

elm-package.json

@@ -9,6 +9,7 @@
     "exposed-modules": [
       "Concurrent"
     ],
+    "native-modules": true,
     "dependencies": {
         "elm-lang/core": "2.0.0 <= v < 3.0.0",
         "imeckler/queue": "1.0.0 <= v < 2.0.0"

src/Concurrent.elm

@@ -26,11 +26,13 @@ https://hackage.haskell.org/package/base/docs/Control-Concurrent-MVar.html
 -}
 
 import Task exposing (Task, andThen, succeed)
+import Native.Concurrent
+import Queue
 
 type MVar a = OpaqueMVar
 
 newEmptyMVar : Task x (MVar a)
-newEmptyMVar = Native.Concurrent.newEmptyMVar
+newEmptyMVar = Native.Concurrent.newEmptyMVar ()
 
 newMVar : a -> Task x (MVar a)
 newMVar value = 

src/Examples/Handoff.elm

@@ -0,0 +1,21 @@
+
+module Handoff where
+
+import Concurrent exposing (MVar, newEmptyMVar, takeMVar, putMVar)
+import Graphics.Element exposing (show)
+import Task exposing (Task, andThen, succeed, spawn)
+
+main = show "Test"
+
+producer : MVar Int -> Task x ()
+producer sync = putMVar sync 5
+
+consumer : MVar Int -> Task x ()
+consumer sync = succeed ()
+
+port startup : Task x ()
+port startup = 
+  newEmptyMVar          `andThen` \sync ->
+  spawn (producer sync) `andThen` \_ ->
+  spawn (consumer sync) `andThen` \_ ->
+  succeed ()

src/Native/Concurrent.js

@@ -12,9 +12,9 @@ Elm.Native.Concurrent.make = function(localRuntime) {
   var Queue = Elm.Queue.make(localRuntime);
   var Task = Elm.Native.Task.make(localRuntime);
 
-  function newEmptyMVar()
+  function newEmptyMVar(_fake)
   {
-    return {
+    return Task.succeed({
       value: Maybe.Nothing,
       consumer: {
         flag: {},
@@ -24,7 +24,7 @@ Elm.Native.Concurrent.make = function(localRuntime) {
         flag: {},
         queue: Queue.empty
       }
-    };
+    });
   }
 
   function _tryWakeup(mvar, name) {
@@ -97,4 +97,9 @@ Elm.Native.Concurrent.make = function(localRuntime) {
     });
   }
 
+  return localRuntime.Native.Concurrent.values = {
+    newEmptyMVar: newEmptyMVar,
+    takeMVar: takeMVar,
+    putMVar: F2(putMVar)
+  };
 }