diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,12 @@
-# Change log
-
-eventsource-api uses [Semantic Versioning][].
-The change log is available through the [releases on GitHub][].
+1.0.2
+=====
+  * Implement essential typesclasses
 
-[Semantic Versioning]: http://semver.org/spec/v2.0.0.html
-[releases on GitHub]: https://github.com/githubuser/eventsource-api/releases
+1.0.1
+=====
+  * Add `forSavedEvents`
+  * Add `foldSavedEventsM`
+  * Add `foldSavedEvents`
+  * Add `foldSubSaved`
+  * Add `foldSubSavedAsync`
+  * Expose `ForEventFailure(..)`
diff --git a/eventsource-api.cabal b/eventsource-api.cabal
--- a/eventsource-api.cabal
+++ b/eventsource-api.cabal
@@ -3,7 +3,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           eventsource-api
-version:        1.0.1
+version:        1.0.2
 synopsis:       Provides a eventsourcing high level API.
 description:    Please read README.md.
 category:       Eventsourcing
diff --git a/library/EventSource/Store.hs b/library/EventSource/Store.hs
--- a/library/EventSource/Store.hs
+++ b/library/EventSource/Store.hs
@@ -215,6 +215,9 @@
   deriving Show
 
 --------------------------------------------------------------------------------
+instance Exception ForEventFailure
+
+--------------------------------------------------------------------------------
 -- | Iterates over all events of stream given a starting point and a batch size.
 forEvents :: (MonadIO m, DecodeEvent a, Store store)
           => store
diff --git a/library/EventSource/Types.hs b/library/EventSource/Types.hs
--- a/library/EventSource/Types.hs
+++ b/library/EventSource/Types.hs
@@ -152,6 +152,17 @@
 newtype EventId = EventId UUID deriving (Eq, Ord)
 
 --------------------------------------------------------------------------------
+instance ToJSON EventId where
+  toJSON (EventId u) = toJSON (toText u)
+
+--------------------------------------------------------------------------------
+instance FromJSON EventId where
+  parseJSON = withText "EventId" $ \t ->
+    case fromText t of
+      Just u  -> return $ EventId u
+      Nothing -> mzero
+
+--------------------------------------------------------------------------------
 instance Show EventId where
   show (EventId uuid) = show uuid
 
@@ -162,7 +173,7 @@
 
 --------------------------------------------------------------------------------
 -- | Represents a stream name.
-newtype StreamName = StreamName Text deriving (Eq, Ord)
+newtype StreamName = StreamName Text deriving (Eq, Ord, ToJSON, FromJSON)
 
 --------------------------------------------------------------------------------
 instance Show StreamName where
@@ -174,7 +185,7 @@
 
 --------------------------------------------------------------------------------
 -- | Used to identity the type of an 'Event'.
-newtype EventType = EventType Text deriving Eq
+newtype EventType = EventType Text deriving (Eq, ToJSON, FromJSON)
 
 --------------------------------------------------------------------------------
 instance Show EventType where
@@ -215,7 +226,8 @@
 
 --------------------------------------------------------------------------------
 -- | Represents an event index in a stream.
-newtype EventNumber = EventNumber Int32 deriving (Eq, Ord, Num, Enum, Show)
+newtype EventNumber = EventNumber Int32
+  deriving (Eq, Ord, Num, Enum, Show, FromJSON, ToJSON)
 
 --------------------------------------------------------------------------------
 -- | Represents an event that's saved into the event store.
@@ -260,6 +272,10 @@
 instance Exception DecodeEventException
 
 --------------------------------------------------------------------------------
+instance EncodeEvent Event where
+  encodeEvent e = put e
+
+--------------------------------------------------------------------------------
 instance DecodeEvent Event where
   decodeEvent = Right
 
@@ -275,7 +291,7 @@
     -- Stream should exist.
   | ExactVersion EventNumber
     -- Stream should be at givent event number.
-  deriving Show
+  deriving (Show, Eq)
 
 --------------------------------------------------------------------------------
 -- | Statuses you can get on every read attempt.
diff --git a/package.yaml b/package.yaml
--- a/package.yaml
+++ b/package.yaml
@@ -29,4 +29,4 @@
 maintainer: yo.eight@gmail.com
 name: eventsource-api
 synopsis: Provides a eventsourcing high level API.
-version: '1.0.1'
+version: '1.0.2'