From 29aaba9386be26d0855c42cbc83d9ba1b9ac26c5 Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Fri, 11 Dec 2015 14:50:03 +0100
Subject: somewhat better name

---
 genEither.hs    | 32 --------------------------------
 nestedEither.hs | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 32 deletions(-)
 delete mode 100644 genEither.hs
 create mode 100644 nestedEither.hs

diff --git a/genEither.hs b/genEither.hs
deleted file mode 100644
index 4f6f7ae..0000000
--- a/genEither.hs
+++ /dev/null
@@ -1,32 +0,0 @@
-#! /usr/bin/env nix-shell
-#! nix-shell -i ghci shell.nix
-  
-{-# LANGUAGE TypeOperators #-}
-{-# LANGUAGE MultiParamTypeClasses #-}
-{-# LANGUAGE FlexibleInstances #-}
-{-# LANGUAGE TypeSynonymInstances #-}
-
-type (:||:) = Either
-infixr 1 :||:
-
-class Contains h n where
-  extract :: h -> Maybe n
-  insert :: n -> h
-
-instance Contains (a :||: b) a where
-  extract (Left a) = Just a
-  extract _ = Nothing
-  insert = Left
-
-instance Contains (a :||: b) b where
-  extract (Right a) = Just a
-  extract _ = Nothing
-  insert = Right
-
-instance {-# OVERLAPS #-} Contains h n => Contains (a :||: h) n where
-  extract (Right a) = extract a
-  extract _ = Nothing
-  insert = Right . insert
-
-test :: Maybe String
-test = extract (insert "test" :: String :||: Integer :||: Float)
diff --git a/nestedEither.hs b/nestedEither.hs
new file mode 100644
index 0000000..64b9412
--- /dev/null
+++ b/nestedEither.hs
@@ -0,0 +1,34 @@
+#! /usr/bin/env nix-shell
+#! nix-shell -i ghci shell.nix
+
+-- Type indexed nested Eithers
+
+{-# LANGUAGE TypeOperators #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE TypeSynonymInstances #-}
+
+type (:||:) = Either
+infixr 1 :||:
+
+class Contains h n where
+  extract :: h -> Maybe n
+  insert :: n -> h
+
+instance Contains (a :||: b) a where
+  extract (Left a) = Just a
+  extract _ = Nothing
+  insert = Left
+
+instance Contains (a :||: b) b where
+  extract (Right a) = Just a
+  extract _ = Nothing
+  insert = Right
+
+instance {-# OVERLAPS #-} Contains h n => Contains (a :||: h) n where
+  extract (Right a) = extract a
+  extract _ = Nothing
+  insert = Right . insert
+
+test :: Maybe String
+test = extract (insert "test" :: String :||: Integer :||: Float)
-- 
cgit v1.2.3