Give User ToJSON instance for as yet unknown reasons

bradparker · bradparker · commit 250be8d5a905 · 2019-10-02T20:32:50.000+10:00
diff --git a/how-does-servants-type-dsl-work.cabal b/how-does-servants-type-dsl-work.cabal
@@ -9,6 +9,7 @@ maintainer:          hi@bradparker.com
 executable server
   main-is:             Main.hs
   build-depends:       base ^>=4.12.0.0
+                     , aeson
                      , servant-server
                      , time
                      , wai
diff --git a/src/Main.hs b/src/Main.hs
@@ -6,6 +6,7 @@
 
 module Main where
 
+import Data.Aeson (ToJSON)
 import Data.Proxy (Proxy(Proxy))
 import Data.Time (Day)
 import GHC.Generics (Generic)
@@ -28,6 +29,8 @@ data User = User
   , registrationDate :: Day
   } deriving (Generic)
 
+instance ToJSON User
+
 type UsersIndex =
   Get '[JSON] [User]
 
