diff --git a/Data/Library.hs b/Data/Library.hs
--- a/Data/Library.hs
+++ b/Data/Library.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE OverloadedStrings,TemplateHaskell #-}
+{-# LANGUAGE OverloadedStrings,TemplateHaskell, BangPatterns #-}
 module Data.Library 
 ( Library
 , ItemId
@@ -20,21 +20,19 @@
 import Data.Text (Text)
 import Data.IntSet (IntSet, insert, empty)
 import qualified Data.IntSet as IS
-import Data.Sequence (Seq, adjust, (|>))
+import Data.Sequence (Seq, (|>))
 import qualified Data.Sequence as Seq
 import Data.Time.Clock (UTCTime)
 import Data.Library.UUIRI (UUIRI, iri, uuid, toUUIRI)
-import Data.Foldable (toList)
-import Data.Aeson (ToJSON(toJSON), FromJSON(parseJSON), object, (.=), (.:), (.:?), (.!=), Value(Object, Null))
-import Data.Aeson.Types (Parser)
 import Control.Applicative ((<$>), (<*>))
 import Control.Monad (mzero)
-import qualified Data.HashMap.Strict as HM
 import Data.SafeCopy (deriveSafeCopy, base)
 import Data.Maybe (fromMaybe)
+import Data.Aeson ( ToJSON(toJSON), FromJSON(parseJSON), object
+                  , (.=), (.:), (.:?), Value(Object, Null))
 
-import Keys.UUID (nil, UUID(..))
-import Data.UUID hiding (nil, UUID)
+import Data.Indexation.UUID hiding (fromText)
+import Data.Indexation.Constraints (Text256, Text4096, fromText)
 
 -- | A Library is just a rebranded Seq
 type Library = Seq LibraryItem
@@ -70,14 +68,14 @@
 
 -- | Changes the name of an item
 rename :: Library -> ItemId -> Text -> UTCTime -> Library
-rename lib target name t = Seq.adjust (setName t name) target lib
+rename lib target name t = Seq.adjust (setName t $ fromText name) target lib
     where
         setName t' n i = i { itemDateModified = t', itemName = n }
 
 -- | Sets the description of an item 
 describe :: Library -> ItemId -> Text -> UTCTime -> Library
 describe lib target description t = 
-    Seq.adjust (setDescription t description) target lib
+    Seq.adjust (setDescription t $ fromText description) target lib
     where
         setDescription t' d i = i { itemDateModified = t'
                                   , itemDescription = Just d }
@@ -86,7 +84,7 @@
 touch :: Library -> ItemId -> UTCTime -> Library
 touch lib target t = Seq.adjust (setTime t) target lib
     where
-        setTime t i = i { itemDateModified = t }
+        setTime t' i = i { itemDateModified = t' }
 
 -- | Create a new item in the library 
 -- If createing a directory then uuiri must be Nothing
@@ -98,8 +96,9 @@
     return $ Seq.update parent up       -- updates the library with it
            $ lib |> i                   -- adds the new item to the library
     where
-        i = Item (Seq.length lib) name description creationTime creationTime 
-                 parent $ maybe (Left (empty, empty)) Right uuiri
+        i = Item (Seq.length lib) (fromText name) (fmap fromText description) 
+                 creationTime creationTime parent $ 
+                 maybe (Left $ Dir empty empty) Right uuiri
 
 -- | No bounds checking and doesn't filter deleted items
 -- returns an exception error when the item is not found
@@ -121,13 +120,13 @@
 itemOpInDir op item dir t = 
     case itemType dir of
         Right _ -> Left $ InvalidDestination (itemId dir)
-        Left (files, dirs) -> Right $ 
+        Left (Dir files dirs) -> Right $ 
             if isDir item 
                 then dir { itemDateModified = t
-                         , itemType = Left (files, op (itemId item) dirs) 
+                         , itemType = Left $ Dir files (op (itemId item) dirs) 
                          }
                 else dir { itemDateModified = t
-                         , itemType = Left (op (itemId item) files, dirs) 
+                         , itemType = Left $ Dir (op (itemId item) files) dirs
                          }
 
 addItemInDir :: LibraryItem -> LibraryItem -> UTCTime 
@@ -144,16 +143,15 @@
 data LibraryItem = 
     Deleted | 
     Item 
-    { itemId           :: ItemId -- root dir is 0
-    , itemName         :: Text
-    , itemDescription  :: Maybe Text -- short description
-    , itemDateCreated  :: UTCTime
-    , itemDateModified :: UTCTime
-    , itemParent       :: ItemId -- root dir has parent = 0
-    , itemType         :: Either Directory UUIRI
+    { itemId           :: !ItemId -- root dir is 0
+    , itemName         :: !Text256
+    , itemDescription  :: !(Maybe Text4096) -- short description
+    , itemDateCreated  :: !UTCTime
+    , itemDateModified :: !UTCTime
+    , itemParent       :: !ItemId -- root dir has parent = 0
+    , itemType         :: !(Either Directory UUIRI)
     } 
 
-
 {-
 testItems t = 
     [ Item 0 "teste" (Just "isto eh um teste") t t 0 (Left (IS.singleton 1,IS.singleton 2))
@@ -169,9 +167,10 @@
         case itype of
             Right f -> ("uuid", toJSON (uuid f)) : ("url", toJSON (iri f)) :
                        ("subdirectories", Null) : ("files",Null) : common
-            Left (f,d) -> ("uuid", Null) : ("url", Null) : 
-                          ("subdirectories", toJSON d) : ("files", toJSON f) : 
-                          common
+            Left (Dir f d) -> 
+                ("uuid", Null) : ("url", Null) : 
+                ("subdirectories", toJSON d) : ("files", toJSON f) : 
+                common
         where 
             common = ["id" .= iid, "name" .= iname, "description" .= idesc
                      , "created" .= icreated, "modified" .= imodified
@@ -195,9 +194,10 @@
                                          Just f -> makeUUIRI fuuid f
         where
             makeDir :: Maybe IntSet -> Maybe IntSet -> Either Directory UUIRI
-            makeDir i1 i2 = Left (fromMaybe (IS.empty) i1, fromMaybe (IS.empty) i2)
+            makeDir i1 i2 = Left $ Dir (fromMaybe (IS.empty) i1) 
+                                       (fromMaybe (IS.empty) i2)
             makeUUIRI :: Maybe UUID -> Text -> Either Directory UUIRI
-            makeUUIRI u iri = Right $ toUUIRI (fromMaybe nil u) iri
+            makeUUIRI u iri' = Right $ toUUIRI (fromMaybe nil u) iri'
     parseJSON _          = mzero
 
 isDir :: LibraryItem -> Bool
@@ -205,9 +205,9 @@
             Right _ -> True
             _ -> False
 
--- | A directory is just a tuple of IntSet's where the first one has the
+-- | A directory is just a pair of IntSet's where the first one has the
 -- files, and the second has the subdirectories 
-type Directory = (IntSet, IntSet) 
+data Directory = Dir !IntSet !IntSet
 
 
 -- | Some errors that might occur
@@ -225,4 +225,5 @@
     return $ newFileText n t c
 -}
 
-deriveSafeCopy 0 'base ''LibraryItem
+$(deriveSafeCopy 0 'base ''Directory)
+$(deriveSafeCopy 0 'base ''LibraryItem)
diff --git a/Data/Library/UUIRI.hs b/Data/Library/UUIRI.hs
--- a/Data/Library/UUIRI.hs
+++ b/Data/Library/UUIRI.hs
@@ -14,19 +14,16 @@
 )
 where
 
-import Data.Text (Text, breakOn, split, splitOn)
-import qualified Data.Text as T 
-import Data.Maybe
+import Data.Text (Text)
 import Data.Library.IRI (IRI, fromIRI)
 import qualified Data.Library.IRI as IRI
-import Keys.UUID (UUID)
 import Data.Aeson (ToJSON(toJSON), FromJSON(parseJSON), object, (.=), (.:), Value(Object))
 import Control.Applicative ((<$>), (<*>))
 import Control.Monad (mzero)
 import Data.SafeCopy (deriveSafeCopy, base)
+import Data.Indexation.UUID (UUID)
 
 newtype UUIRI = UUIRI (UUID, IRI) 
-deriveSafeCopy 0 'base ''UUIRI -- from Data.SafeCopy
 
 instance Eq UUIRI where
     uuiri1 == uuiri2 = uuid uuiri1 == uuid uuiri2
@@ -52,7 +49,7 @@
 
 -- | returns the UUIRI tuple with the IRI translated to Text
 fromUUIRI :: UUIRI -> (UUID, Text)
-fromUUIRI (UUIRI (u,iri)) = (u, IRI.fromIRI iri)
+fromUUIRI (UUIRI (u,iri')) = (u, IRI.fromIRI iri')
 
 -- | is the IRI part of the UUIRI a relative IRI ?
 isRelative :: UUIRI -> Bool
@@ -78,3 +75,4 @@
 dirs :: UUIRI -> [Text]
 dirs = IRI.dirs . iri
 
+$(deriveSafeCopy 0 'base ''UUIRI) -- from Data.SafeCopy
diff --git a/dirfiles.cabal b/dirfiles.cabal
--- a/dirfiles.cabal
+++ b/dirfiles.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                dirfiles
-version:             0.1.0.1
+version:             0.1.0.2
 -- synopsis:            
 description:         Simple datatype to represent a library with files and folders
 license:             BSD3
@@ -19,6 +19,13 @@
   exposed-modules:     Data.Library, Data.Library.UUIRI, Data.Library.IRI
   -- other-modules:       
   other-extensions:    OverloadedStrings, TemplateHaskell
-  build-depends:       base >=4.6 && <4.7, text >=0.11 && <0.12, containers >=0.5 && <0.6, time >=1.4 && <1.5, aeson >=0.6 && <0.7, unordered-containers >=0.2 && <0.3, safecopy >=0.8 && <0.9, special-keys >=0.1 && <0.2
+  build-depends: base                   >=4.6  && <4.7
+               ,    text >=0.11 
+               ,    containers >=0.5 
+               ,    time >=1.4 
+               ,    aeson >=0.6 
+               ,    unordered-containers >=0.2 && <0.3
+               ,    safecopy >=0.8 
+               ,    hblock >=0.1 
   -- hs-source-dirs:      
   default-language:    Haskell2010