diff --git a/Examples/fancyhdr.hs b/Examples/fancyhdr.hs
--- a/Examples/fancyhdr.hs
+++ b/Examples/fancyhdr.hs
@@ -1,4 +1,6 @@
 
+{-# LANGUAGE OverloadedStrings #-}
+
 import Text.LaTeX
 import Text.LaTeX.Packages.Fancyhdr
 
diff --git a/Examples/tikz.hs b/Examples/tikz.hs
--- a/Examples/tikz.hs
+++ b/Examples/tikz.hs
@@ -42,6 +42,6 @@
  center $ tikzpicture $
       draw (Start (pointAtXY   0    1) ->- pointAtXY  0     (-1))
   ->> draw (Start (pointAtXY (-0.2) 0) ->- pointAtXY (3*pi)   0 )
-  ->> scope [TColor Blue, TWidth (Pt 1)] (draw $ bpath (pointAtXY 0 0) $
+  ->> scope [TColor $ BasicColor Blue, TWidth (Pt 1)] (draw $ bpath (pointAtXY 0 0) $
         mapM_ line [ pointAtXY x (sin x) | x <- [0,0.05 .. 3*pi] ]
              )
diff --git a/HaTeX.cabal b/HaTeX.cabal
--- a/HaTeX.cabal
+++ b/HaTeX.cabal
@@ -1,5 +1,5 @@
 Name: HaTeX
-Version: 3.11.0.1
+Version: 3.12.0.0
 Author: Daniel Díaz
 Category: Text, LaTeX
 Build-type: Simple
@@ -89,7 +89,7 @@
           Text.LaTeX.Packages.TikZ.Simple
           Text.LaTeX.Packages.TikZ.Syntax
   Other-modules: Paths_HaTeX
-  Default-extensions: OverloadedStrings
+  Default-extensions: OverloadedStrings, TypeFamilies
   Other-extensions: CPP
   ghc-options: -Wall -fno-warn-orphans
 
diff --git a/Text/LaTeX/Base/Parser.hs b/Text/LaTeX/Base/Parser.hs
--- a/Text/LaTeX/Base/Parser.hs
+++ b/Text/LaTeX/Base/Parser.hs
@@ -28,7 +28,7 @@
 import           Data.Text (Text)
 import qualified Data.Text as T 
 
-import           Control.Applicative ((<|>), (<$>))
+import           Control.Applicative ((<|>), (<$>),many)
 import           Control.Monad (unless)
 
 import           Text.LaTeX.Base.Syntax
@@ -99,13 +99,15 @@
 env = do
   _  <- char '\\'
   n  <- envName "begin"
-  skipSpace
+  sps <- many $ char ' '
+  let lsps = if null sps then mempty else TeXRaw $ T.pack sps
   as <- cmdArgs
   b  <- envBody n 
   return $ TeXEnv (T.unpack n) (fromMaybe [] as) $
-    if as == Just []
-       then TeXBraces mempty <> b
-       else b
+    case as of
+     Just [] -> lsps <> TeXBraces mempty <> b
+     Nothing -> lsps <> b
+     _ -> b
 
 envName :: Text -> Parser Text
 envName k = do
diff --git a/Text/LaTeX/Base/Writer.hs b/Text/LaTeX/Base/Writer.hs
--- a/Text/LaTeX/Base/Writer.hs
+++ b/Text/LaTeX/Base/Writer.hs
@@ -1,4 +1,6 @@
 
+{-# LANGUAGE TypeFamilies #-}
+
 -- | The writer monad applied to 'LaTeX' values. Useful to compose 'LaTeX' values
 --   using the @do@ notation:
 --
@@ -20,7 +22,6 @@
 -- > anotherExample :: LaTeXT IO ()
 -- > anotherExample = lift (readFileTex "foo") >>= verbatim
 --
---
 -- This way, it is easy (without carrying arguments) to include IO outputs
 -- in the LaTeX document, like files, times or random objects.
 --
@@ -29,8 +30,6 @@
 --
 -- Of course, you can always use the simpler interface provided by the plain 'LaTeX' type.
 --
--- Another thing you should know about the LaTeX Writer Monad. Don't try to get values
--- from computations with no results (like @raw "foo"@).
 module Text.LaTeX.Base.Writer
  ( -- * @LaTeXT@ writer
    LaTeXT
@@ -49,9 +48,6 @@
  , rendertexM
  , liftFun
  , liftOp
-   -- * Errors
- , throwError
- , merror
    -- * Re-exports
  , lift
  , liftIO
@@ -76,18 +72,14 @@
 
 -- | 'WriterT' monad transformer applied to 'LaTeX' values.
 newtype LaTeXT m a =
-  LaTeXT { unwrapLaTeXT :: WriterT LaTeX m (a,Maybe String) }
+  LaTeXT { unwrapLaTeXT :: WriterT LaTeX m a }
 
 instance Functor f => Functor (LaTeXT f) where
- fmap f = LaTeXT . fmap (first f) . unwrapLaTeXT
-
--- | Pair a value with 'Nothing'.
-pairNoth :: a -> (a,Maybe b)
-pairNoth x = (x,Nothing)
+ fmap f = LaTeXT . fmap f . unwrapLaTeXT
 
 instance Applicative f => Applicative (LaTeXT f) where
- pure = LaTeXT . pure . pairNoth
- (LaTeXT f) <*> (LaTeXT x) = LaTeXT $ fmap (first . fst) f <*> x
+ pure = LaTeXT . pure
+ (LaTeXT f) <*> (LaTeXT x) = LaTeXT $ f <*> x
 
 -- | Type synonym for empty 'LaTeXT' computations.
 type LaTeXT_ m = LaTeXT m ()
@@ -99,7 +91,7 @@
 --
 -- > runLaTeXM = runIdentity . runLaTeXT
 --
-runLaTeXM :: LaTeXM a -> (Either String a, LaTeX)
+runLaTeXM :: LaTeXM a -> (a, LaTeX)
 runLaTeXM = runIdentity . runLaTeXT
 
 -- | A particular case of 'execLaTeXT'.
@@ -110,31 +102,25 @@
 execLaTeXM = runIdentity . execLaTeXT
 
 instance MonadTrans LaTeXT where
- lift = LaTeXT . liftM pairNoth . lift
+ lift = LaTeXT . lift
 
 instance Monad m => Monad (LaTeXT m) where
- return = LaTeXT . return . pairNoth
+ return = LaTeXT . return
  (LaTeXT c) >>= f = LaTeXT $ do 
-  (a,_) <- c
+  a <- c
   let LaTeXT c' = f a
   c'
- fail = throwError
+ fail = return . error
 
 instance MonadIO m => MonadIO (LaTeXT m) where
  liftIO = lift . liftIO
 
-instance Monad m => LaTeXC (LaTeXT m a) where
- liftListL f xs = mapM extractLaTeX_ xs >>= merror "liftListL" . textell . f
+instance (Monad m, a ~ ()) => LaTeXC (LaTeXT m a) where
+ liftListL f xs = mapM extractLaTeX_ xs >>= textell . f
 
--- | Running a 'LaTeXT' computation returns the final 'LaTeX' value
---   and either a 'String' if the computation didn't contain any value
---   or the value itself otherwise.
-runLaTeXT :: Monad m => LaTeXT m a -> m (Either String a,LaTeX)
-runLaTeXT (LaTeXT c) = runWriterT c >>= (
-  \((a,m),l) -> case m of
-             Nothing  -> return (Right a ,l)
-             Just err -> return (Left err,l)
-       )
+-- | Running a 'LaTeXT' computation returns the final 'LaTeX' value.
+runLaTeXT :: Monad m => LaTeXT m a -> m (a,LaTeX)
+runLaTeXT = runWriterT . unwrapLaTeXT
 
 -- | This is the usual way to run the 'LaTeXT' monad
 --   and obtain a 'LaTeX' value.
@@ -159,9 +145,7 @@
 -- | This function run a 'LaTeXT' computation,
 --   lifting the result again in the monad.
 extractLaTeX :: Monad m => LaTeXT m a -> LaTeXT m (a,LaTeX)
-extractLaTeX (LaTeXT c) = LaTeXT $ do
- ((a,m),l) <- lift $ runWriterT c
- return ((a,l),m)
+extractLaTeX = LaTeXT . lift . runWriterT . unwrapLaTeXT
 
 -- | Executes a 'LaTeXT' computation, embedding it again in
 --   the 'LaTeXT' monad.
@@ -178,7 +162,7 @@
 -- | With 'textell' you can append 'LaTeX' values to the
 --   state of the 'LaTeXT' monad.
 textell :: Monad m => LaTeX -> LaTeXT m ()
-textell = LaTeXT . liftM pairNoth . tell
+textell = LaTeXT . tell
 
 -- | Lift a function over 'LaTeX' values to a function
 --   acting over the state of a 'LaTeXT' computation.
@@ -211,26 +195,11 @@
 rendertexM :: (Render a, Monad m) => a -> LaTeXT m ()
 rendertexM = textell . rendertex
 
--- Error throwing
-
--- | The 'fail' method of the 'LaTeXT' monad.
-throwError :: Monad m => String -> LaTeXT m a
-throwError = LaTeXT . return . (error &&& Just)
-
--- | Function 'merror' casts a value contained in a monad @m@ to the
---   bottom value of another type. If you try to evaluate this value, you will
---   get an error message with the 'String' passed as argument to 'merror'.
-merror :: Monad m => String -> LaTeXT m a -> LaTeXT m b
-merror = flip (>>) . throwError
-
 -- Overloaded Strings
 
--- | Be careful when using 'fromString' over a 'LaTeXT' value,
---   the returned value of the computation is bottom (i.e. 'undefined').
-instance Monad m => IsString (LaTeXT m a) where
- fromString = merror "LaTeXT: fromString!" . textell . fromString
+instance (Monad m, a ~ ()) => IsString (LaTeXT m a) where
+ fromString = textell . fromString
 
--- | 'mappend' @=@ '>>'.
-instance Monad m => Monoid (LaTeXT m a) where
- mempty = throwError "LaTeXT: mempty!"
+instance (Monad m, a ~ ()) => Monoid (LaTeXT m a) where
+ mempty = return ()
  mappend = (>>)
diff --git a/Text/LaTeX/Packages/AMSMath.hs b/Text/LaTeX/Packages/AMSMath.hs
--- a/Text/LaTeX/Packages/AMSMath.hs
+++ b/Text/LaTeX/Packages/AMSMath.hs
@@ -1,5 +1,6 @@
-{-# LANGUAGE OverloadedStrings #-}
 
+{-# LANGUAGE OverloadedStrings, TypeFamilies #-}
+
 -- | \AMSMath\ support. Also numeric instances ('Num', 'Fractional' and 'Floating') for 'LaTeX' and 'LaTeXT'.
 module Text.LaTeX.Packages.AMSMath
  ( -- * AMSMath package
@@ -179,17 +180,17 @@
 
 -- | Warning: this instance only exists for the 'Num' instance.
 --   This instance is defined in the "Text.LaTeX.Packages.AMSMath" module.
-instance Monad m => Eq (LaTeXT m a) where
+instance Eq (LaTeXT m a) where
  _ == _ = error "Cannot use \"(==)\" Eq method with a LaTeXT value."
 
 -- | Warning: this instance only exists for the 'Num' instance.
 --   This instance is defined in the "Text.LaTeX.Packages.AMSMath" module.
-instance Monad m => Show (LaTeXT m a) where
+instance Show (LaTeXT m a) where
  show _ = error "Cannot use \"show\" Show method with a LaTeXT value."
 
 -- | Careful! Method 'signum' is undefined. Don't use it!
 --   This instance is defined in the "Text.LaTeX.Packages.AMSMath" module.
-instance Monad m => Num (LaTeXT m a) where
+instance (Monad m, a ~ ()) => Num (LaTeXT m a) where
  (+) = liftOp (+)
  (-) = liftOp (-)
  (*) = (>>)
@@ -201,13 +202,13 @@
 
 -- | Division uses the LaTeX 'frac' command.
 --   This instance is defined in the "Text.LaTeX.Packages.AMSMath" module.
-instance Monad m => Fractional (LaTeXT m a) where
+instance (Monad m, a ~ ()) => Fractional (LaTeXT m a) where
  (/) = liftOp (/)
  fromRational = fromLaTeX . fromRational
 
 -- | Undefined methods: 'asinh', 'atanh' and 'acosh'.
 --   This instance is defined in the "Text.LaTeX.Packages.AMSMath" module.
-instance Monad m => Floating (LaTeXT m a) where
+instance (Monad m, a ~ ()) => Floating (LaTeXT m a) where
  pi = pi_
  exp = liftFun exp
  sqrt = liftFun sqrt