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author | Gregor Kleen <gkleen@yggdrasil.li> | 2015-08-12 14:26:36 +0200 |
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committer | Gregor Kleen <gkleen@yggdrasil.li> | 2015-08-12 14:26:36 +0200 |
commit | a568e0ccde5a9914512e3d3f5af850b4a652e47f (patch) | |
tree | 4bac262a3ac9eedc15ff9b777fc532712e46c289 /provider/posts | |
parent | a986d02401388cd0c89a816a3307496d40d4c8bf (diff) | |
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beuteltier-3.md
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1 | --- | ||
2 | title: An Update to the Type Level Utilities of an Overly Complicated Feedreader | ||
3 | published: 2015-08-12 | ||
4 | tags: Beuteltier | ||
5 | --- | ||
6 | |||
7 | I commited a change to `beuteltier/Beuteltier/Types/Util.hs` ("[…] Hashable update"). I | ||
8 | replaced the `Hashable` instances for `Object` and `MetaData` with a single, better | ||
9 | optimized function: | ||
10 | |||
11 | ~~~ {.haskell .numberLines} | ||
12 | objHash :: Applicative f => ObjectGen f -> f Int | ||
13 | -- ^ Two 'ObjectGen's hashes are a first indication of whether they are 'Equivalent' | ||
14 | objHash o = fmap hash $ (,) <$> (Set.toList . (^. mTags) <$> o ^. oMeta) <*> (Map.keys <$> o ^. oContent) | ||
15 | ~~~ | ||
16 | |||
17 | The new implementation allows computation of hashes without calling `generateObject` (that | ||
18 | function is evil — it makes sure the entire `Object` is "in RAM" (it isn´t actually, of | ||
19 | course (because haskell is lazy)—but I have no guarantee of that)). | ||