Rename Elem to Find.

semantic-tags/src/AST/Element.hs

@@ -12,8 +12,8 @@ class Element sub sup where
   -- | Project one element out of a sum type.
   prj :: sup a -> Maybe (sub a)
 
-instance (Element' elem sub sup, elem ~ Elem sub sup) => Element sub sup where
+instance (Element' side sub sup, side ~ Find sub sup) => Element sub sup where
-  prj = prj' @elem
+  prj = prj' @side
 
 
 pattern Prj :: Element sub sup => sub a -> sup a
@@ -21,21 +21,21 @@ pattern Prj sub <- (prj -> Just sub)
 
 data Side = None | Here | L | R
 
-type family Elem sub sup :: Side where
+type family Find sub sup :: Side where
-  Elem t t         = 'Here
+  Find t t         = 'Here
-  Elem t (l :+: r) = Elem' 'L t l <> Elem' 'R t r
+  Find t (l :+: r) = Find' 'L t l <> Find' 'R t r
-  Elem _ _         = 'None
+  Find _ _         = 'None
 
-type family Elem' (side :: Side) sub sup :: Side where
+type family Find' (side :: Side) sub sup :: Side where
-  Elem' s t t         = s
+  Find' s t t         = s
-  Elem' s t (l :+: r) = Elem' s t l <> Elem' s t r
+  Find' s t (l :+: r) = Find' s t l <> Find' s t r
-  Elem' _ _ _         = 'None
+  Find' _ _ _         = 'None
 
 type family (a :: Side) <> (b :: Side) :: Side where
   'None <> b = b
   a     <> _ = a
 
-class Element' (elem :: Side) sub sup where
+class Element' (side :: Side) sub sup where
   prj' :: sup a -> Maybe (sub a)
 
 instance {-# OVERLAPPABLE #-}