+ Document generics.

2 files changed, 23 insertions, 1 deletions

diff --git a/TODO.org b/TODO.org
index 5f18148..eed927c 100644
--- a/TODO.org
+++ b/TODO.org
@@ -3,7 +3,7 @@
 * DONE lens compatible selectors renaming
 * DONE benchmarks for generic decode
 * DONE documentation
-* TODO document generics
+* DONE document generics
 * TODO v0.2.0.0 (reason: dictAssoc is hidded now)
 * TODO use HashMap
 * TODO CPS Result
diff --git a/src/Data/BEncode.hs b/src/Data/BEncode.hs
index f41e4b8..d18d787 100644
--- a/src/Data/BEncode.hs
+++ b/src/Data/BEncode.hs
@@ -158,6 +158,28 @@ type Result = Either String
 
 -- | This class is used to define new datatypes that could be easily
 -- serialized using bencode format.
+--
+--   By default 'BEncodable' have a generic implementation; suppose
+--   the following datatype:
+--
+-- > data List a = Cons { _head  :: a
+-- >                    , __tail :: (List a) }
+-- >             | Nil
+-- >               deriving Generic
+--
+--   If we don't need to obey any particular specification or
+--   standard, the default instance could be derived automatically
+--   from the 'Generic' instance:
+--
+-- > instance BEncodable a => BEncodable (List a)
+--
+--   Example of derived 'toBEncode' result:
+--
+-- > > toBEncode (Cons 123 $ Cons 1 Nil)
+-- > BDict (fromList [("head",BInteger 123),("tail",BList [])])
+--
+--  Note that '_' prefixes are omitted.
+--
 class BEncodable a where
   -- | See an example of implementation here 'Assoc'
   toBEncode   :: a -> BEncode