allow building with transformers >= 0.6 (#56)

Author: lambdageek

src/Unbound/Generics/LocallyNameless/Fresh.hs

@@ -30,7 +30,9 @@ import Control.Monad.Fix (MonadFix)
 #endif
 import Control.Monad.Trans
 import Control.Monad.Trans.Except
+#if !MIN_VERSION_transformers(0,6,0)
 import Control.Monad.Trans.Error
+#endif
 import Control.Monad.Trans.Maybe
 import Control.Monad.Trans.Reader
 import Control.Monad.Trans.State.Lazy as Lazy
@@ -119,8 +121,10 @@ instance Monad m => Fresh (FreshMT m) where
     return $ (Fn s n)
   fresh nm@(Bn {}) = return nm
 
+#if !MIN_VERSION_transformers(0,6,0)
 instance (Error e, Fresh m) => Fresh (ErrorT e m) where
   fresh = lift . fresh
+#endif
 
 instance Fresh m => Fresh (ExceptT e m) where
   fresh = lift . fresh

src/Unbound/Generics/LocallyNameless/LFresh.hs

@@ -77,10 +77,14 @@ import Control.Monad.Identity
 import Control.Applicative (Applicative, Alternative)
 
 import Control.Monad.Trans.Cont
+#if !MIN_VERSION_transformers(0,6,0)
 import Control.Monad.Trans.Error
+#endif
 import Control.Monad.Trans.Except
 import Control.Monad.Trans.Identity
+#if !MIN_VERSION_transformers(0,6,0)
 import Control.Monad.Trans.List
+#endif
 import Control.Monad.Trans.Maybe
 import Control.Monad.Trans.State.Lazy as Lazy
 import Control.Monad.Trans.State.Strict as Strict
@@ -164,10 +168,12 @@ instance LFresh m => LFresh (ContT r m) where
   avoid  = mapContT . avoid
   getAvoids = lift getAvoids
 
+#if !MIN_VERSION_transformers(0,6,0)
 instance (Error e, LFresh m) => LFresh (ErrorT e m) where
   lfresh = lift . lfresh
   avoid  = mapErrorT . avoid
   getAvoids = lift getAvoids
+#endif
 
 instance LFresh m => LFresh (ExceptT e m) where
   lfresh = lift . lfresh
@@ -179,10 +185,12 @@ instance LFresh m => LFresh (IdentityT m) where
   avoid  = mapIdentityT . avoid
   getAvoids = lift getAvoids
 
+#if !MIN_VERSION_transformers(0,6,0)
 instance LFresh m => LFresh (ListT m) where
   lfresh = lift . lfresh
   avoid  = mapListT . avoid
   getAvoids = lift getAvoids
+#endif
 
 instance LFresh m => LFresh (MaybeT m) where
   lfresh = lift . lfresh

unbound-generics.cabal

@@ -56,7 +56,7 @@ library
                        template-haskell >= 2.8.0.0,
                        deepseq >= 1.3.0.0,
                        mtl >= 2.1,
-                       transformers >= 0.3 && < 0.6,
+                       transformers >= 0.3 && < 0.7,
                        transformers-compat >= 0.3,
                        containers >= 0.5 && < 0.7,
                        contravariant >= 0.5,