Add IsForeign instance for JSDate

Author: garyb

bower.json

@@ -18,6 +18,7 @@
   "dependencies": {
     "purescript-datetime": "^1.0.0",
     "purescript-exceptions": "^1.0.0",
+    "purescript-foreign": "^1.0.0",
     "purescript-integers": "^1.0.0"
   },
   "devDependencies": {

src/Data/JSDate.purs

@@ -19,6 +19,8 @@ import Data.DateTime as DateTime
 import Data.DateTime.Instant (Instant)
 import Data.DateTime.Instant as Instant
 import Data.Enum (fromEnum)
+import Data.Foreign (unsafeReadTagged)
+import Data.Foreign.Class (class IsForeign)
 import Data.Function.Uncurried (Fn2, runFn2)
 import Data.Int (toNumber)
 import Data.Maybe (Maybe(..))
@@ -28,6 +30,9 @@ import Data.Time.Duration (Milliseconds(..))
 -- | The type of JavaScript `Date` objects.
 foreign import data JSDate :: *
 
+instance isForeignJSDate :: IsForeign JSDate where
+  read = unsafeReadTagged "Date"
+
 -- | Checks whether a date value is valid. When a date is invalid, the majority
 -- | of the functions return `NaN`, `"Invalid Date"`, or throw an exception.
 foreign import isValid :: JSDate -> Boolean

test/Test/Main.js

@@ -0,0 +1,3 @@
+"use strict";
+
+exports.myDate = new Date();

test/Test/Main.purs

@@ -5,19 +5,27 @@ import Prelude
 import Control.Monad.Eff (Eff)
 import Control.Monad.Eff.Console (CONSOLE, log)
 
+import Data.DateTime as DT
 import Data.Enum (toEnum)
+import Data.Either (isRight)
+import Data.Foreign (F, Foreign)
+import Data.Foreign.Class (read)
 import Data.JSDate as JSD
-import Data.DateTime as DT
 import Data.Maybe (Maybe(..), fromJust)
 import Partial.Unsafe (unsafePartial)
 
 import Global (nan)
 
 import Test.Assert (ASSERT, assert)
 
+foreign import myDate :: Foreign
+
 main :: forall eff. Eff (console :: CONSOLE, assert :: ASSERT, locale :: JSD.LOCALE | eff) Unit
 main = do
 
+  log "Check IsForeign intance will read JS date values..."
+  assert $ isRight $ read myDate :: F JSD.JSDate
+
   log "Checking that a UTC date constructed with sensible values is valid..."
   assert $ JSD.isValid $ JSD.jsdate defaultDateRecord