Add support for multiple levels

Add a data structure, based on the zipper comonad, which provides
support for multiple levels, each of which is its own entity map. The
current level is provided by coreturn, which the `entities` lens has
been updated to use. Nothing currently supports going up or down levels
yet - that's coming next.

1 files changed, 92 insertions, 0 deletions

diff --git a/build/update-comonad-extras.patch b/build/update-comonad-extras.patch
new file mode 100644
index 000000000000..cd1dbe24d361
--- /dev/null
+++ b/build/update-comonad-extras.patch
@@ -0,0 +1,92 @@
+diff --git a/comonad-extras.cabal b/comonad-extras.cabal
+index fc3745a..77a2f0d 100644
+--- a/comonad-extras.cabal
++++ b/comonad-extras.cabal
+@@ -1,7 +1,7 @@
+ name:          comonad-extras
+ category:      Control, Comonads
+-version:       4.0
++version:       5.0
+ x-revision: 1
+ license:       BSD3
+ cabal-version: >= 1.6
+ license-file:  LICENSE
+@@ -34,8 +34,8 @@ library
+   build-depends:
+     array                >= 0.3   && < 0.6,
+-    base                 >= 4     && < 4.7,
+-    containers           >= 0.4   && < 0.6,
+-    comonad              >= 4     && < 5,
++    base                 >= 4     && < 5,
++    containers           >= 0.6   && < 0.7,
++    comonad              >= 5     && < 6,
+     distributive         >= 0.3.2 && < 1,
+-    semigroupoids        >= 4     && < 5,
+-    transformers         >= 0.2   && < 0.4
++    semigroupoids        >= 5     && < 6,
++    transformers         >= 0.5   && < 0.6
+
+   exposed-modules:
+     Control.Comonad.Store.Zipper
+diff --git a/src/Control/Comonad/Store/Pointer.hs b/src/Control/Comonad/Store/Pointer.hs
+index 5044a1e..8d4c62d 100644
+--- a/src/Control/Comonad/Store/Pointer.hs
++++ b/src/Control/Comonad/Store/Pointer.hs
+@@ -41,7 +41,6 @@ module Control.Comonad.Store.Pointer
+   , module Control.Comonad.Store.Class
+   ) where
+
+-import Control.Applicative
+ import Control.Comonad
+ import Control.Comonad.Hoist.Class
+ import Control.Comonad.Trans.Class
+@@ -51,27 +50,8 @@ import Control.Comonad.Env.Class
+ import Data.Functor.Identity
+ import Data.Functor.Extend
+ import Data.Array
+-
+ #ifdef __GLASGOW_HASKELL__
+ import Data.Typeable
+-instance (Typeable i, Typeable1 w) => Typeable1 (PointerT i w) where
+-  typeOf1 diwa = mkTyConApp storeTTyCon [typeOf (i diwa), typeOf1 (w diwa)]
+-    where
+-      i :: PointerT i w a -> i
+-      i = undefined
+-      w :: PointerT i w a -> w a
+-      w = undefined
+-
+-instance (Typeable i, Typeable1 w, Typeable a) => Typeable (PointerT i w a) where
+-  typeOf = typeOfDefault
+-
+-storeTTyCon :: TyCon
+-#if __GLASGOW_HASKELL__ < 704
+-storeTTyCon = mkTyCon "Control.Comonad.Trans.Store.Pointer.PointerT"
+-#else
+-storeTTyCon = mkTyCon3 "comonad-extras" "Control.Comonad.Trans.Store.Pointer" "PointerT"
+-#endif
+-{-# NOINLINE storeTTyCon #-}
+ #endif
+
+ type Pointer i = PointerT i Identity
+@@ -83,6 +63,9 @@ runPointer :: Pointer i a -> (Array i a, i)
+ runPointer (PointerT (Identity f) i) = (f, i)
+
+ data PointerT i w a = PointerT (w (Array i a)) i
++#ifdef __GLASGOW_HASKELL__
++  deriving Typeable
++#endif
+
+ runPointerT :: PointerT i w a -> (w (Array i a), i)
+ runPointerT (PointerT g i) = (g, i)
+diff --git a/src/Control/Comonad/Store/Zipper.hs b/src/Control/Comonad/Store/Zipper.hs
+index 3b70c86..decc378 100644
+--- a/src/Control/Comonad/Store/Zipper.hs
++++ b/src/Control/Comonad/Store/Zipper.hs
+@@ -15,7 +15,6 @@
+ module Control.Comonad.Store.Zipper
+   ( Zipper, zipper, zipper1, unzipper, size) where
+
+-import Control.Applicative
+ import Control.Comonad (Comonad(..))
+ import Data.Functor.Extend
+ import Data.Foldable