diff --git a/indexation.cabal b/indexation.cabal
--- a/indexation.cabal
+++ b/indexation.cabal
@@ -1,5 +1,5 @@
 name: indexation
-version: 0.3.0.2
+version: 0.4
 category: Data
 synopsis: Tools for entity indexation
 description: A set of tools for indexing entities
diff --git a/library/Indexation/Data.hs b/library/Indexation/Data.hs
--- a/library/Indexation/Data.hs
+++ b/library/Indexation/Data.hs
@@ -3,8 +3,16 @@
   Index(..),
   EntityTable,
   Indexer,
+  lookupEntity,
 )
 where
 
+import Indexation.Prelude
 import Indexation.Types
 import Indexation.Instances ()
+import qualified Data.Vector as Vector
+
+
+lookupEntity :: Index entity -> EntityTable entity -> Maybe entity
+lookupEntity (Index indexPrim) (EntityTable vector) =
+  vector Vector.!? indexPrim
diff --git a/library/Indexation/Instances.hs b/library/Indexation/Instances.hs
--- a/library/Indexation/Instances.hs
+++ b/library/Indexation/Instances.hs
@@ -6,7 +6,7 @@
 import Indexation.Instances.Cereal ()
 
 
-deriving instance Show (Index a)
+instance Show (Index a) where show (Index int) = show int
 deriving instance Eq (Index a)
 deriving instance Ord (Index a)
 deriving instance Hashable (Index a)