Work on orienting positions for attachment items

src/SimpleTrie.hs

@@ -1,42 +1,48 @@
 {-# LANGUAGE TemplateHaskell #-}
+
 module SimpleTrie where
-import qualified Data.Map.Strict as M
+
 import Control.Lens
+import qualified Data.Map.Strict as M
+
 data Trie a b = Trie
-    { _trieMVal    :: Maybe b
+    { _trieMVal :: Maybe b
     , _trieChildren :: M.Map a (Trie a b)
     }
+
 makeLenses ''Trie
 
 emptyTrie :: Trie a b
 emptyTrie = Trie Nothing M.empty
 
 singletonTrie :: Ord a => [a] -> b -> Trie a b
-singletonTrie (k:ks) x = Trie Nothing $ M.singleton k $ singletonTrie ks x
+singletonTrie (k : ks) x = Trie Nothing $ M.singleton k $ singletonTrie ks x
 singletonTrie [] x = Trie (Just x) M.empty
 
 insertInTrie :: Ord a => [a] -> b -> Trie a b -> Trie a b
-insertInTrie [] x      = trieMVal ?~ x
-insertInTrie (k:ks) x  = trieChildren %~ M.insertWith f k (singletonTrie ks x)
+insertInTrie [] x = trieMVal ?~ x
+insertInTrie (k : ks) x = trieChildren %~ M.insertWith f k (singletonTrie ks x)
   where
     f _ = insertInTrie ks x
 
 lookupTrie :: Ord a => [a] -> Trie a b -> Maybe b
-lookupTrie (k:ks) t = _trieChildren t M.!? k >>= lookupTrie ks
-lookupTrie []     t = _trieMVal t
+lookupTrie (k : ks) t = _trieChildren t M.!? k >>= lookupTrie ks
+lookupTrie [] t = _trieMVal t
 
-multiLookupTrie :: Ord a => [a] -> Trie a b -> [([a],b)]
-multiLookupTrie  xs t@(Trie my ch)
-    | null xs || null ch = maybe [] (\y -> [([],y)]) my
-    | otherwise = let (z:zs) = xs in
-        case M.lookup z ch of
-            Nothing -> multiLookupTrie zs t
-            Just t' -> map (_1 %~ (z:)) (multiLookupTrie zs t') ++ multiLookupTrie zs t
+multiLookupTrie :: Ord a => [a] -> Trie a b -> [([a], b)]
+multiLookupTrie xs t@(Trie my ch)
+    | null xs || null ch = maybe [] (\y -> [([], y)]) my
+    | otherwise =
+        let (z : zs) = xs
+         in case M.lookup z ch of
+                Nothing -> multiLookupTrie zs t
+                Just t' -> map (_1 %~ (z :)) (multiLookupTrie zs t') ++ multiLookupTrie zs t
 
-multiLookupTrieI :: Ord a => [(a,c)] -> Trie a b -> [([c],b)]
-multiLookupTrieI  xs t@(Trie my ch)
-    | null xs || null ch = maybe [] (\y -> [([],y)]) my
-    | otherwise = let ((z1,z2):zs) = xs in
-        case M.lookup z1 ch of
-            Nothing -> multiLookupTrieI zs t
-            Just t' -> map (_1 %~ (z2:)) (multiLookupTrieI zs t') ++ multiLookupTrieI zs t
+multiLookupTrieI :: Ord a => [(a, c)] -> Trie a b -> [([c], b)]
+multiLookupTrieI xs t@(Trie my ch)
+    | null xs || null ch = maybe [] (\y -> [([], y)]) my
+    | otherwise =
+        let ((z1, z2) : zs) = xs
+         in case M.lookup z1 ch of
+                Nothing -> multiLookupTrieI zs t
+                Just t' -> map (_1 %~ (z2 :)) (multiLookupTrieI zs t') ++ multiLookupTrieI zs t