From a568e0ccde5a9914512e3d3f5af850b4a652e47f Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Wed, 12 Aug 2015 14:26:36 +0200
Subject: beuteltier-3.md

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+---
+title: An Update to the Type Level Utilities of an Overly Complicated Feedreader
+published: 2015-08-12
+tags: Beuteltier
+---
+
+I commited a change to `beuteltier/Beuteltier/Types/Util.hs` ("[…] Hashable update"). I
+replaced the `Hashable` instances for `Object` and `MetaData` with a single, better
+optimized function:
+
+~~~ {.haskell .numberLines}
+objHash :: Applicative f => ObjectGen f -> f Int
+-- ^ Two 'ObjectGen's hashes are a first indication of whether they are 'Equivalent'
+objHash o = fmap hash $ (,) <$> (Set.toList . (^. mTags) <$> o ^. oMeta) <*> (Map.keys <$> o ^. oContent)
+~~~
+
+The new implementation allows computation of hashes without calling `generateObject` (that
+function is evil — it makes sure the entire `Object` is "in RAM" (it isn´t actually, of
+course (because haskell is lazy)—but I have no guarantee of that)).
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