Merge branch 'master' of git.yggdrasil.li:dirty-haskell.org

1 files changed, 11 insertions, 5 deletions

diff --git a/provider/posts/beuteltier-2.lhs b/provider/posts/beuteltier-2.lhs
index bca4c86..d5e0294 100644
--- a/provider/posts/beuteltier-2.lhs
+++ b/provider/posts/beuteltier-2.lhs
@@ -53,6 +53,9 @@ mostly of the canonical invocations of
 > import Data.Map (Map)
 > import qualified Data.Map as Map
 > 
+> import Data.Set (Set)
+> import qualified Data.Set as Set
+> 
 > import Data.Hashable (Hashable(..), hashUsing)
 > 
 > import Data.Monoid ((<>))
@@ -66,10 +69,10 @@ Quite often we find ourselves in the position that we want to alter some small p
 complicated structure. We would therefore like to write the following:
 
 ~~~ {.haskell .numberLines}
-updateFoo :: Monad m => Foo -> m Foo
-updateFoo = alter $ do
-  bar <~ constructNewBarInM
-  buz .= makeConstantBuz
+updateFoo :: Foo -> Monad Foo
+updateFoo x = alter x $ do
+  bar <~ (constructNewBar :: Monad Bar)
+  buz .= (makeConstantBuz :: Buz)
 ~~~
 
 The definitions below allow us not only to do so, but also provide some convenience
@@ -113,7 +116,7 @@ Sometimes we just really want to translate an `ObjectGen` to an `Object`.
 >   oMeta .= return (obj ^. oMeta')
 
 We expect implementations of `insert` to perform what we call nubbing. That is removal of
-'Object's that are, in some sense, `Equivalent` to the new one we´re currently
+`Object`s that are, in some sense, `Equivalent` to the new one we´re currently
 inserting. Thus we provide a definition of what we mean, when we say `Equivalent`.
 
 > class Equivalent a where
@@ -150,6 +153,9 @@ all objects sharing a hash to determine true equivalency.
 > -- | Two 'Object's´ hashes are a first indication of whether they are 'Equivalent'
 > instance Hashable Object where
 >   hashWithSalt = hashUsing $ \a -> (a ^. oMeta', Map.keys $ content a)
+>
+> instance Hashable MetaData where
+>   hashWithSalt = hashUsing $ Set.toList . (^. mTags)
 > 
 > content :: Object -> Map SubObjectName (Maybe SubObject)
 > content obj = promised obj <> actual obj