Stubbing out some of the timezone conversions

Data/Time/Cube.hs

@@ -18,6 +18,7 @@ module Data.Time.Cube
   -- * Time conversions
   , convertDateTime
   , convertDateTimeZone
+  , convertTimeZone
 
   -- * Raw date components
   , DateTimeStruct(..)
@@ -46,6 +47,7 @@ module Data.Time.Cube
 
 import Prelude hiding ((.), id)
 
+import Data.Time.Cube.TimeZone
 import Data.Time.Cube.Types
 import Data.Time.Cube.UnixTime
 

Data/Time/Cube/TimeZone.hs

@@ -0,0 +1,60 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+module Data.Time.Cube.TimeZone
+  ( convertTimeZone
+  , convertDateTimeZone
+  ) where
+
+import Control.Monad.Trans (MonadIO, liftIO)
+import Data.Time.Cube.Types
+import Data.Time.Cube.UnixTime
+
+-- class Monad m => TimeZoneSeries2 m (tz :: TimeZone) where
+  -- convertToUTC   :: UnixTimeNanos tz -> m (UnixTimeNanos 'UTC)
+  -- convertFromUTC :: UnixTimeNanos 'UTC -> m (UnixTimeNanos tz)
+
+class Monad m => TimeZoneSeries2 (from :: TimeZone) m (to :: TimeZone) where
+  convertTimeZone :: UnixTimeNanos from -> m (UnixTimeNanos to)
+
+getLocalTimeZone :: Monad m => m String
+getLocalTimeZone = return "US/Pacific"
+
+instance MonadIO m => TimeZoneSeries2 'UTC m 'LocalTime where
+  convertTimeZone t = do
+    localTimeZone <- liftIO getLocalTimeZone
+    case localTimeZone of
+      "US/Eastern" -> do
+        -- UnixTimeNanos (s, ns) :: UnixTimeNanos '(TimeZone "US/Pacific") <- convertTimeZone t
+        UnixTimeNanos (s, ns) :: UnixTimeNanos 'USEastern <- convertTimeZone t
+        return $! UnixTimeNanos (s, ns) 
+
+      "US/Pacific" -> do
+        -- UnixTimeNanos (s, ns) :: UnixTimeNanos '(TimeZone "US/Pacific") <- convertTimeZone t
+        UnixTimeNanos (s, ns) :: UnixTimeNanos 'USPacific <- convertTimeZone t
+        return $! UnixTimeNanos (s, ns) 
+
+instance Monad m => TimeZoneSeries2 'UTC m 'USPacific where
+  convertTimeZone (UnixTimeNanos (s, ns)) = return $! UnixTimeNanos (s-28800, ns)
+
+instance Monad m => TimeZoneSeries2 'UTC m 'USEastern where
+  convertTimeZone (UnixTimeNanos (s, ns)) = return $! UnixTimeNanos (s-18000, ns)
+
+instance Monad m => TimeZoneSeries2 tz m tz where
+  convertTimeZone = return
+
+convertToUTC
+  :: (TimeZoneSeries2 tz m 'UTC)
+  => UnixTimeNanos tz -> m (UnixTimeNanos 'UTC)
+convertToUTC = convertTimeZone
+
+convertDateTimeZone
+  :: (DateTime f, DateTime t)
+  => f
+  -> IO t
+convertDateTimeZone = undefined
+

Data/Time/Cube/Types.hs

@@ -16,7 +16,6 @@ module Data.Time.Cube.Types
 
   -- * Time conversions
   , convertDateTime
-  , convertDateTimeZone
 
   -- * Date sections
   , Epoch
@@ -179,7 +178,8 @@ deriving instance Show   Pico
 deriving instance Num    Pico
 deriving instance NFData Pico
 
-data TimeZone = UTC | LocalTime -- NamedTimeZone String
+data TimeZone = UTC | LocalTime | USEastern | USPacific -- | forall a . TimeZone a
+  deriving (Show, Eq, Ord)
 
 class DateTime f where
   -- |
@@ -213,12 +213,6 @@ convertDateTime
   -> Maybe t
 convertDateTime = undefined
 
-convertDateTimeZone
-  :: (DateTime f, DateTime t)
-  => f
-  -> IO t
-convertDateTimeZone = undefined
-
 class Duration (a :: *)
 
 instance Duration Year

Data/Time/Cube/UnixTime.hs

@@ -18,10 +18,6 @@ module Data.Time.Cube.UnixTime
   , getCurrentUnixTime
   , getCurrentUnixTimeNanos
 
-  -- * Time conversions
-  , convertDateTime
-  , convertDateTimeZone
-
   -- * Raw date components
   , DateTimeStruct(..)