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authorGriffin Smith <root@gws.fyi>2019-08-31T17·17-0400
committerGriffin Smith <root@gws.fyi>2019-08-31T17·18-0400
commit4ef19aa35a6d63a8d9f7b6a7a11ac82c2a525783 (patch)
tree00a0109cca42bbdda93fa117142d381501c1bf00 /src/Xanthous/Orphans.hs
parent6eba471e2426e7e4e7d5c935e3ce973e13fd6b24 (diff)
Add entities, and allow walking around
Add support for entities via a port of the EntityMap type, and implement
command support starting at basic hjkl.
Diffstat (limited to 'src/Xanthous/Orphans.hs')
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1 files changed, 23 insertions, 0 deletions
diff --git a/src/Xanthous/Orphans.hs b/src/Xanthous/Orphans.hs
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+++ b/src/Xanthous/Orphans.hs
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+{-# LANGUAGE UndecidableInstances, PatternSynonyms #-}
+{-# OPTIONS_GHC -Wno-orphans #-}
+-- |
+
+module Xanthous.Orphans () where
+
+import Xanthous.Prelude
+
+instance forall s a.
+  ( Cons s s a a
+  , MonoFoldable s
+  ) => Cons (NonNull s) (NonNull s) a a where
+  _Cons = prism hither yon
+    where
+      hither :: (a, NonNull s) -> NonNull s
+      hither (a, ns) =
+        let s = toNullable ns
+        in impureNonNull $ a <| s
+
+      yon :: NonNull s -> Either (NonNull s) (a, NonNull s)
+      yon ns = case ns ^? _Cons of
+        Nothing -> Left ns
+        Just (a, ns') -> Right (a, ns')