Implement saving+loading the game

Implement ToJSON and FromJSON for all of the various pieces of the game
state, and add a pair of functions saveGame/loadGame implementing a
prism to save the game as zlib-compressed JSON. To test this, there's
now Arbitrary, CoArbitrary, and Function instances for all the parts of
the game state - to get around circular imports with the concrete
entities this unfortunately is happening via orphan instances, plus an
hs-boot file to break a circular import that was just a little too hard
to remove by moving things around. Ugh.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/Xanthous/Game/Arbitrary.hs b/src/Xanthous/Game/Arbitrary.hs
index 5bba77d5a174..e8f9ae22c461 100644
--- a/src/Xanthous/Game/Arbitrary.hs
+++ b/src/Xanthous/Game/Arbitrary.hs
@@ -1,4 +1,6 @@
+{-# LANGUAGE UndecidableInstances #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
+{-# LANGUAGE StandaloneDeriving #-}
 {-# LANGUAGE RecordWildCards #-}
 --------------------------------------------------------------------------------
 module Xanthous.Game.Arbitrary where
@@ -9,7 +11,7 @@ import           Test.QuickCheck
 import           System.Random
 --------------------------------------------------------------------------------
 import           Xanthous.Game.State
-import           Xanthous.Entities.Arbitrary ()
+import           Xanthous.Entities.Entities ()
 import           Xanthous.Entities.Character
 import qualified Xanthous.Data.EntityMap as EntityMap
 --------------------------------------------------------------------------------
@@ -26,3 +28,8 @@ instance Arbitrary GameState where
     let _promptState = NoPrompt -- TODO
     _debugState <- arbitrary
     pure $ GameState {..}
+
+
+instance CoArbitrary GameState
+instance Function GameState
+deriving newtype instance CoArbitrary (m (a, GameState)) => CoArbitrary (AppT m a)