From 73403d9c236cce99608b08faca9e599fb0fb099d Mon Sep 17 00:00:00 2001
From: Gabriel Gonzalez <Gabriel439@gmail.com>
Date: Mon, 23 Aug 2021 21:02:06 -0700
Subject: [PATCH 1/2] `FromDhall` / `ToDhall` instances for temporal values

Fixes https://github.com/dhall-lang/dhall-haskell/issues/2286
---
 dhall/src/Dhall/Marshal/Decode.hs | 44 +++++++++++++++++++++++++++++++
 dhall/src/Dhall/Marshal/Encode.hs | 22 ++++++++++++++++
 2 files changed, 66 insertions(+)

diff --git a/dhall/src/Dhall/Marshal/Decode.hs b/dhall/src/Dhall/Marshal/Decode.hs
index 6bbdffc9a..8ceb5cafd 100644
--- a/dhall/src/Dhall/Marshal/Decode.hs
+++ b/dhall/src/Dhall/Marshal/Decode.hs
@@ -56,6 +56,10 @@ module Dhall.Marshal.Decode
     , string
     , lazyText
     , strictText
+      -- ** Time
+    , timeOfDay
+    , day
+    , timeZone
       -- ** Containers
     , maybe
     , pair
@@ -164,6 +168,7 @@ import qualified Data.Sequence
 import qualified Data.Set
 import qualified Data.Text
 import qualified Data.Text.Lazy
+import qualified Data.Time            as Time
 import qualified Data.Vector
 import qualified Dhall.Core           as Core
 import qualified Dhall.Map
@@ -893,6 +898,45 @@ strictText = Decoder {..}
 
     expected = pure Text
 
+{-| Decode `Time.TimeOfDay`
+
+>>> input timeOfDay "00:00:00"
+00:00:00
+-}
+timeOfDay :: Decoder Time.TimeOfDay
+timeOfDay = Decoder {..}
+  where
+    extract (TimeLiteral t _) = pure t
+    extract  expr             = typeError expected expr
+
+    expected = pure Time
+
+{-| Decode `Time.Day`
+
+>>> input day "2000-01-01"
+2000-01-01
+-}
+day :: Decoder Time.Day
+day = Decoder {..}
+  where
+    extract (DateLiteral d) = pure d
+    extract  expr           = typeError expected expr
+
+    expected = pure Date
+
+{-| Decode `Time.TimeZone`
+
+>>> input timeZone "+00:00"
++0000
+-}
+timeZone :: Decoder Time.TimeZone
+timeZone = Decoder {..}
+  where
+    extract (TimeZoneLiteral z) = pure z
+    extract  expr               = typeError expected expr
+
+    expected = pure TimeZone
+
 {-| 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 4cca05f6b..545ae6f82 100644
--- a/dhall/src/Dhall/Marshal/Encode.hs
+++ b/dhall/src/Dhall/Marshal/Encode.hs
@@ -82,6 +82,7 @@ import qualified Data.Sequence
 import qualified Data.Set
 import qualified Data.Text
 import qualified Data.Text.Lazy
+import qualified Data.Time            as Time
 import qualified Data.Vector
 import qualified Data.Void
 import qualified Dhall.Core           as Core
@@ -311,6 +312,27 @@ instance ToDhall a => ToDhall [a] where
 instance ToDhall a => ToDhall (Vector a) where
     injectWith = fmap (contramap Data.Vector.toList) injectWith
 
+instance ToDhall Time.TimeOfDay where
+    injectWith _ = Encoder {..}
+      where
+        embed timeOfDay = TimeLiteral timeOfDay 12
+
+        declared = Time
+
+instance ToDhall Time.Day where
+    injectWith _ = Encoder {..}
+      where
+        embed = DateLiteral
+
+        declared = Date
+
+instance ToDhall Time.TimeZone where
+    injectWith _ = Encoder {..}
+      where
+        embed = TimeZoneLiteral
+
+        declared = TimeZone
+
 {-| Note that the output list will be sorted.
 
 >>> let x = Data.Set.fromList ["mom", "hi" :: Text]

From 4946c115f90dddb5fd8421141cc4aad87fa468d6 Mon Sep 17 00:00:00 2001
From: Gabriel Gonzalez <Gabriel439@gmail.com>
Date: Wed, 1 Sep 2021 21:40:26 -0700
Subject: [PATCH 2/2] Add missing `FromDhall` instances
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

… as caught by @sjakobi
---
 dhall/src/Dhall/Marshal/Decode.hs | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/dhall/src/Dhall/Marshal/Decode.hs b/dhall/src/Dhall/Marshal/Decode.hs
index 8ceb5cafd..d66338902 100644
--- a/dhall/src/Dhall/Marshal/Decode.hs
+++ b/dhall/src/Dhall/Marshal/Decode.hs
@@ -313,6 +313,15 @@ instance FromDhall a => FromDhall [a] where
 instance FromDhall a => FromDhall (Vector a) where
     autoWith opts = vector (autoWith opts)
 
+instance FromDhall Time.TimeOfDay where
+    autoWith _ = timeOfDay
+
+instance FromDhall Time.Day where
+    autoWith _ = day
+
+instance FromDhall Time.TimeZone where
+    autoWith _ = timeZone
+
 {-| Note that this instance will throw errors in the presence of duplicates in
     the list. To ignore duplicates, use `setIgnoringDuplicates`.
 -}