diff --git a/TTTAS.cabal b/TTTAS.cabal
--- a/TTTAS.cabal
+++ b/TTTAS.cabal
@@ -1,7 +1,7 @@
 cabal-version:      >=1.2.3
 build-type:         Simple
 name:               TTTAS
-version:            0.4.1
+version:            0.4.2
 license:            LGPL
 license-file:       COPYRIGHT
 maintainer:         Marcos Viera <mviera@fing.edu.uy>
@@ -12,7 +12,7 @@
 copyright:          Universiteit Utrecht
 extra-source-files: README, LICENSE-LGPL, TTTAS.bib
 library
-        build-depends:      base >= 4 && < 5, haskell98
+        build-depends:      base >= 4 && < 5
         exposed-modules:    Language.AbstractSyntax.TTTAS       
         extensions:         Arrows, KindSignatures, RankNTypes, GADTs, CPP
         hs-source-dirs:     src
diff --git a/src/Language/AbstractSyntax/TTTAS.hs b/src/Language/AbstractSyntax/TTTAS.hs
--- a/src/Language/AbstractSyntax/TTTAS.hs
+++ b/src/Language/AbstractSyntax/TTTAS.hs
@@ -317,6 +317,8 @@
               in (b,t1,e1,f')
             ))
 
+
+
 -- | The combinator 'sequenceA' sequentially composes a list
 --   of 'Trafo's into a 'Trafo' that yields a list of outputs.
 --   Its use is analogous to the combinator 'sequence' combinator
@@ -332,7 +334,6 @@
 
 
 
-
 -- | Alternative version of 'Trafo' where the universal quantification 
 --   over |s| is moved inside the quantification over |env2|.
 --   Note that the type variables |a| and |b| are now labelled with |s|, 
@@ -391,11 +392,11 @@
 
 newtype Pair a b s = P (a s, b s)
 
-class Category2 cat where
+class Category2 (cat :: (* -> *) -> (* -> *) -> *) where
   id2     :: cat a a
   (.:.)   :: cat b c -> cat a b -> cat a c
 
-class Category2 arr => Arrow2 arr where
+class Category2 arr => Arrow2 (arr :: (* -> *) -> (* -> *) -> *) where
   arr2    :: (forall s . a s -> b s) -> arr a b
   first2  :: arr a b -> arr (Pair a c) (Pair b c)
   second2 :: arr a b -> arr (Pair c a) (Pair c b)