From b42f489e341cc038d431412bf7d4381049044902 Mon Sep 17 00:00:00 2001
From: amesgen <amesgen@amesgen.de>
Date: Sat, 11 Sep 2021 12:59:47 +0200
Subject: [PATCH] Add `FromDhall`/`ToDhall` for
 `LocalTime`/`ZonedTime`/`UTCTime`

---
 dhall/src/Dhall/Marshal/Decode.hs | 45 +++++++++++++++++++++++++++++++
 dhall/src/Dhall/Marshal/Encode.hs | 20 ++++++++++++++
 2 files changed, 65 insertions(+)

diff --git a/dhall/src/Dhall/Marshal/Decode.hs b/dhall/src/Dhall/Marshal/Decode.hs
index 5b533585b6..745298f197 100644
--- a/dhall/src/Dhall/Marshal/Decode.hs
+++ b/dhall/src/Dhall/Marshal/Decode.hs
@@ -60,6 +60,9 @@ module Dhall.Marshal.Decode
     , timeOfDay
     , day
     , timeZone
+    , localTime
+    , zonedTime
+    , utcTime
       -- ** Containers
     , maybe
     , pair
@@ -326,6 +329,15 @@ instance FromDhall Time.Day where
 instance FromDhall Time.TimeZone where
     autoWith _ = timeZone
 
+instance FromDhall Time.LocalTime where
+    autoWith _ = localTime
+
+instance FromDhall Time.ZonedTime where
+    autoWith _ = zonedTime
+
+instance FromDhall Time.UTCTime where
+    autoWith _ = utcTime
+
 {-| Note that this instance will throw errors in the presence of duplicates in
     the list. To ignore duplicates, use `setIgnoringDuplicates`.
 -}
@@ -950,6 +962,39 @@ timeZone = Decoder {..}
 
     expected = pure TimeZone
 
+{-| Decode `Time.LocalTime`
+
+>>> input localTime "2020-01-01T12:34:56"
+2020-01-01 12:34:56
+-}
+localTime :: Decoder Time.LocalTime
+localTime = record $
+  Time.LocalTime
+    <$> field "date" day
+    <*> field "time" timeOfDay
+
+{-| Decode `Time.ZonedTime`
+
+>>> input zonedTime "2020-01-01T12:34:56+02:00"
+2020-01-01 12:34:56 +02:00
+-}
+zonedTime :: Decoder Time.ZonedTime
+zonedTime = record $
+  adapt
+    <$> field "date" day
+    <*> field "time" timeOfDay
+    <*> field "timeZone" timeZone
+  where
+    adapt date time = Time.ZonedTime (Time.LocalTime date time)
+
+{-| Decode `Time.UTCTime`
+
+>>> input utcTime "2020-01-01T12:34:56+02:00"
+2020-01-01 10:34:56 UTC
+-}
+utcTime :: Decoder Time.UTCTime
+utcTime = Time.zonedTimeToUTC <$> zonedTime
+
 {-| Decode a `Maybe`.
 
 >>> input (maybe natural) "Some 1"
diff --git a/dhall/src/Dhall/Marshal/Encode.hs b/dhall/src/Dhall/Marshal/Encode.hs
index 545ae6f822..5223ef7639 100644
--- a/dhall/src/Dhall/Marshal/Encode.hs
+++ b/dhall/src/Dhall/Marshal/Encode.hs
@@ -333,6 +333,26 @@ instance ToDhall Time.TimeZone where
 
         declared = TimeZone
 
+instance ToDhall Time.LocalTime where
+    injectWith _ = recordEncoder $
+      adapt
+        >$< encodeField "date"
+        >*< encodeField "time"
+      where
+        adapt (Time.LocalTime date time) = (date, time)
+
+instance ToDhall Time.ZonedTime where
+    injectWith _ = recordEncoder $
+      adapt
+        >$< encodeField "date"
+        >*< encodeField "time"
+        >*< encodeField "timeZone"
+      where
+        adapt (Time.ZonedTime (Time.LocalTime date time) timeZone) = (date, (time, timeZone))
+
+instance ToDhall Time.UTCTime where
+    injectWith = contramap (Time.utcToZonedTime Time.utc) . injectWith
+
 {-| Note that the output list will be sorted.
 
 >>> let x = Data.Set.fromList ["mom", "hi" :: Text]