+
+
+-- | Compute size of an arbitrary data structure
+gsize :: Data a => a -> Int
+gsize t = 1 + sum (gmapQ gsize t)
+
+
+-- | Count the number of immediate subterms of the given term
+glength :: GenericQ Int
+glength = length . gmapQ (const ())
+
+
+-- | Determine depth of the given term
+gdepth :: GenericQ Int
+gdepth = (+) 1 . foldr max 0 . gmapQ gdepth
+
+
+-- | Determine the number of all suitable nodes in a given term
+gcount :: GenericQ Bool -> GenericQ Int
+gcount p = everything (+) (\x -> if p x then 1 else 0)
+
+
+-- | Determine the number of all nodes in a given term
+gnodecount :: GenericQ Int
+gnodecount = gcount (const True)
+
+
+-- | Determine the number of nodes of a given type in a given term
+gtypecount :: Typeable a => a -> GenericQ Int
+gtypecount (_::a) = gcount (False `mkQ` (\(_::a) -> True))
+
+
+-- | Find (unambiguously) an immediate subterm of a given type
+gfindtype :: (Data x, Data y) => x -> Maybe y
+gfindtype = singleton
+ . foldl unJust []
+ . gmapQ (Nothing `mkQ` Just)
+ where
+ unJust l (Just x) = x:l
+ unJust l Nothing = l
+ singleton [s] = Just s
+ singleton _ = Nothing