diff --git a/HJavaScript.cabal b/HJavaScript.cabal
--- a/HJavaScript.cabal
+++ b/HJavaScript.cabal
@@ -1,20 +1,21 @@
 Name:             HJavaScript
-Version:          0.4
+Version:          0.4.4
 License:          BSD3
 Author:           Joel Bjornson, Niklas Broberg
 Maintainer:       joel.bjornson@gmail.com, nibro@cs.chalmers.se
 
-Synopsis:	  HJavaScript is an abstract syntax for a typed subset of JavaScript.
-Description:	  HJavaScript defines an abstract syntax and pretty printer for
-		  a subset of JavaScript. as Language.HJavaScript. However, a significant 
-		  difference from JavaScript is that HJavaScript is typed, even on the 
-		  abstract syntax level using GADTs. The subset of JavaScript that is 
-		  supported is those parts that lend themself to typing 
-		  (i.e. no prototyping of classes).
+Synopsis:         HJavaScript is an abstract syntax for a typed subset of JavaScript.
+Description:      HJavaScript defines an abstract syntax and pretty printer for
+                  a subset of JavaScript. as Language.HJavaScript. However, a significant 
+                  difference from JavaScript is that HJavaScript is typed, even on the 
+                  abstract syntax level using GADTs. The subset of JavaScript that is 
+                  supported is those parts that lend themself to typing 
+                  (i.e. no prototyping of classes).
 
 
+Hs-Source-Dirs:   src
 Exposed-Modules:  Language.HJavaScript.Syntax
 
 Build-Depends:    base
 Build-Type:       Simple
-Category:	  Language
+Category:         Language
diff --git a/Language/HJavaScript/Syntax.hs b/Language/HJavaScript/Syntax.hs
deleted file mode 100644
--- a/Language/HJavaScript/Syntax.hs
+++ /dev/null
@@ -1,556 +0,0 @@
-{-# OPTIONS_GHC -fglasgow-exts #-}
-{-# OPTIONS_GHC -fallow-overlapping-instances #-}
-{-# OPTIONS_GHC -fallow-undecidable-instances #-}
------------------------------------------------------------------------------
--- |
--- Module      :  Language.HJavaScript.Syntax
--- Copyright   :  (c) Joel Bjornson 2008
--- License     :  BSD-style
--- Maintainer  :  Joel Bjornson joel.bjornson@gmail.com
---                Niklas Broberg nibro@cs.chalmers.se
--- Stability   :  experimental
------------------------------------------------------------------------------
-module Language.HJavaScript.Syntax
-  (
-    -- * Primitive type classes.
-    JType,
-        
-    -- * Fundamental data types.
-    Exp(..),
-    Var(..),
-    Stmt(..),
-    Block(..),
-    
-    -- * Data types and classes for object representation.
-    IsClass,
-    HasConstructor,
-    IsDeref,
-    
-    -- * Misc
-    AssignOp(..),
-    BinOp(..),
-    PlusOpType,    
-    PostPre(..),
-    Elses(..),
-    IsNullable,
-    IsFeature,
-    JShow(..),
-     
-    -- * Types for functions and parameters.
-    Args,
-    ParamType,
-    FormalParams(..),
-        
-    -- * Array representation.
-    Array(..),
-       
-    -- * Type synonyms.
-    JInt, JString, JBool, JFloat, JVoid, JObject, JArray,
-    
-    -- * Type classes for expression representation.
-    IsExp(..), 
-    IsJString(..),
-    IsJBool(..),
-    IsJInt(..),
-    IsJFloat(..),
-    
-    -- * Helper functions
-    val, toBlock, deref, derefVar, 
-    methodCall, voidMethodCall, 
-    methodCallNoArgs, voidMethodCallNoArgs
-     
-  ) where
-   
-import Data.Char
-import Data.Maybe
-
--- | JavaScript types
-class JType t
-instance JType String
-instance JType Int
-instance JType Bool
-instance JType ()
-instance JType Float
-instance IsClass c => JType c
-instance (Show t1, JType t1, Show t2, JType t2) => JType (t1 -> t2)
-
--------------------------------------------------------------------
--- JavaScript variable and expression representation
--------------------------------------------------------------------
-
--- Var represents JavaScript variables.
-data Var t where
-  JVar          :: String -> Var a
-  JParam        :: Int -> Var a
-  JMember       :: String -> Var a
-  JDerefVar     :: IsDeref d => d -> String -> Var a
-  JArrayIndex   :: Exp (Array t) -> Exp Int -> Var t
-
-instance Show (Var t) where
-  showsPrec p var  = case var of
-    JVar v           -> showString v
-    JParam n         -> showString "param" . shows n
-    JMember s        -> showString s
-    JDerefVar o v    -> shows o . sDot . showString v
-    JArrayIndex a ix ->  shows a . showString "[" . 
-                               shows ix . showString "]"
-
-
--- Exp represents JavaScript Expressions.
-data Exp t where
-  JInt         :: Int    -> Exp Int
-  JFloat       :: Float  -> Exp Float
-  JBool        :: Bool   -> Exp Bool
-  JString      :: String -> Exp String
-  JConst       :: String -> Exp t
-  JAssign      :: Var t -> Exp t -> Exp t
-  JAssignWith  :: Var t -> AssignOp t -> Exp t -> Exp t
-  JNeg         :: Exp t -> Exp t
-  JNot         :: Exp Bool -> Exp Bool
-  JBinOp       :: Exp t -> BinOp t r -> Exp t -> Exp r
-  JIncrement   :: Num t => PostPre -> Var t -> Exp t
-  JDecrement   :: Num t => PostPre -> Var t -> Exp t
-  JIfOp        :: Exp Bool -> Exp t -> Exp t -> Exp t
-  JCall        :: (Args e t) => Exp (t -> r) -> e -> Exp r
-  JNew         :: (Args e t,  HasConstructor c e t) => c -> e -> Exp c
-  JDeref       :: IsDeref d => d -> String -> Exp t
-  JFunction    :: FormalParams a t => Maybe String -> a -> Block r -> Exp (t -> r)
-  JThis        :: IsClass c => Exp c
-  JBlock       :: Block () -> Exp ()
-  JNull        :: IsNullable t => Exp t
-  JCastObject  :: (IsClass c1, IsClass c2) => Exp c1 -> Exp c2
-  JValueOf     :: Var t -> Exp t
-  JIsImpl      :: (IsClass c , IsFeature f) => Exp c -> f -> Exp Bool
-  JShow        :: JShow t => Exp t -> Exp String
-  
-
--------------------------------------------------------------------
--- | Show for Exp
--------------------------------------------------------------------
-instance Show (Exp t) where
-  showsPrec p exp = case exp of
-    JInt n                 ->  shows n
-    JFloat f               ->  shows f
-    JBool b                ->  if b then 
-                                  showString "true" 
-                                else 
-                                  showString "false"
-    JString s              ->  sJtr s
-    JConst c               ->  showString c
-    JAssign e1 e2          ->  shows e1 . sEq . shows e2
-    JAssignWith e1 op e2   ->  shows e1 . shows op . shows e2
-    JNeg e                 ->  showString "-" . (showParen True $ shows e)
-    JNot e                 ->  showString "!" . (showParen True $ shows e)
-    JBinOp e1 op e2        ->  shows e1 . shows op . shows e2
-    JIncrement pp e        ->  if (pp == Pre) then 
-                                  (showString "++" . shows e) 
-                                else 
-                                  (shows e . showString "++")
-    JDecrement pp e        ->  if (pp == Pre) then 
-                                  (showString "--" . shows e) 
-                                else 
-                                  (shows e . showString "--")
-    JIfOp e1 e2 e3         ->  shows e1 . showString "?" . shows e2 . 
-                               showString ":" . shows e3
-    JCall x a2             ->  shows x . showsArgs a2
-    JNew c a               ->  showString "new" . sSpace . shows c . showsArgs a
-    JDeref o e             ->  shows o . sDot . showString e
-    JFunction n fp b       ->  showString "function" .
-                                sSpace .
-                                sMaybe n . 
-                                showsFParams fp . 
-                                sBrack b
-    JThis                  ->  showString "this"
-    JBlock b               ->  shows b
-    JNull                  ->  showString "null"
-    JIsImpl ob c           ->  shows ob . sDot . showsFeature c
-    JValueOf v             ->  shows v
-    JCastObject e          ->  shows e
-    JShow e                ->  shows e
-
-
-
--------------------------------------------------------------------
--- Type synonyms for Exp.
--------------------------------------------------------------------
-type JInt       = Exp Int
-type JString    = Exp String
-type JBool      = Exp Bool
-type JFloat     = Exp Float
-type JVoid      = Exp ()
-type JObject c  = Exp c
-type JArray t   = Exp (Array t)
-
-
--------------------------------------------------------------------
--- Additional classes
--------------------------------------------------------------------
-
--- | Class for representing JavaScript "features", e.g. names of 
--- objects or functions. Example:  window `hasFeature` "alert"
-class Show a => IsFeature a where
-  showsFeature :: a -> ShowS
-
--- A class can be a feature
-instance IsClass c => IsFeature c where
-  showsFeature = shows
-  
-
--- | Any string value can be a feature.
-instance IsFeature String where
-  showsFeature = showString
-
-
--- | Class that represents showable types
-class JShow a where
- jshow :: a -> JString
-
-instance JShow Int where
- jshow = jshow . JInt
-
-instance JShow Float where
- jshow = jshow . JFloat
- 
-instance JShow Bool where
- jshow = jshow . JBool
- 
-instance JShow String where
- jshow = JString
-
-instance JShow a => JShow (Exp a) where
- jshow = JShow
-
--- | Allows values to be compared to JNull. E.g. for checking that
--- an object is instantiated or is accessible.
-class IsNullable a
-
--- | All JString values along with all objects can be nulll.
-instance IsNullable String
-instance IsClass c => IsNullable c
-
--------------------------------------------------------------------
--- JavaScript statements representation
--------------------------------------------------------------------
--- | Post or Pre prefix , i.e. --x or x++
-data PostPre = Pst | Pre deriving Eq
-
-
--- | Assign Operator
-data AssignOp t where
-  PlusAssign  :: Num t => AssignOp t
-  MinusAssign :: Num t => AssignOp t
-  TimesAssign :: Num t => AssignOp t
-  DivAssign   :: AssignOp Float
-  ModAssign   :: AssignOp Int
-  AndAssign   :: AssignOp Bool
-  OrAssign    :: AssignOp Bool
-
-instance Show (AssignOp t) where
-  showsPrec p exp = case exp of
-    PlusAssign  -> showString "+="
-    MinusAssign -> showString "-="
-    TimesAssign -> showString "*="
-    DivAssign   -> showString "/="
-    ModAssign   -> showString "%="
-    AndAssign   -> showString "&="
-    OrAssign    -> showString "|="
-      
-
--- | Class for expression that may be "plussed".
--- Examples: 1 + 2, "ha" + "skell".
-class PlusOpType a 
-instance PlusOpType String
-instance PlusOpType Int
-instance PlusOpType Float
-
--- | Binary Operator
-data BinOp t r where
-  Plus        :: PlusOpType t => BinOp t t  
-  Minus       :: Num t => BinOp t t
-  Times       :: Num t => BinOp t t
-  Div         :: Num t => BinOp t t
-  Mod         :: BinOp Int Int
-  And         :: BinOp Bool Bool
-  Or          :: BinOp Bool Bool
-  Equals      :: BinOp t Bool
-  NotEquals   :: BinOp t Bool
-  GThan       :: Num t => BinOp t Bool
-  LThan       :: Num t => BinOp t Bool
-  GEThan      :: Num t => BinOp t Bool
-  LEThan      :: Num t => BinOp t Bool
-  
-
-instance Show (BinOp t r) where
-  showsPrec p exp = case exp of
-    Plus      -> showString " + "
-    Minus     -> showString " - "
-    Times     -> showString " * "
-    Div       -> showString " / "
-    Mod       -> showString " % "
-    And       -> showString " && "
-    Or        -> showString " || "
-    Equals    -> showString " == "
-    NotEquals -> showString " != "
-    GThan     -> showString " > "
-    LThan     -> showString " < "
-    GEThan    -> showString " >= "
-    LEThan    -> showString " <= "
-    
-    
-data Stmt t where
-  VarDecl       :: String -> Stmt ()
-  VarDeclAssign :: String -> Exp t -> Stmt ()
-  VarAssign     :: String -> Exp t -> Stmt ()
-  ExpStmt       :: Exp t -> Stmt ()
-  While         :: Exp Bool -> Block () -> Stmt ()
-  DoWhile       :: Block () -> Exp Bool -> Stmt ()
-  For           :: Stmt t1 -> Exp Bool -> Exp t2 -> Block () -> Stmt ()  
-  Break         :: Stmt ()
-  Continue      :: Stmt ()
-  Return        :: Exp t -> Stmt t
-  If            :: Exp Bool -> Block t -> Elses t -> Stmt ()
-  
-data Elses t where
-  Elseif  :: Exp Bool -> Block t -> Elses t -> Elses t
-  Else    :: Block t -> Elses t
-  NoElse  :: Elses ()  
-  
-instance Show (Stmt t) where
-  showsPrec p stm = case stm of
-    VarDecl s         ->  showString "var" . sSpace . showString s
-    VarAssign s e     ->  showString s . showString " = " . shows e
-    VarDeclAssign s e ->  showString "var" . sSpace . showString s .  
-                          showString " = " . shows e 
-    ExpStmt e         ->  shows e
-    While e b         ->  showString "while" . showParen True (shows e) . 
-                          sBrack b
-    DoWhile b e       ->  showString "do" . sBrack b . showString "while" . 
-                          showParen True (shows e)
-    For e1 e2 e3 b    ->  showString "for" . 
-                          showParen True (shows e1 . sc . shows e2 . 
-                          sc . shows e3) . sBrack b
-    Break             ->  showString "break"
-    Continue          ->  showString "continue"
-    Return e          ->  showString "return" . showString " " . shows e
-    If e1 b1 b2       ->  showString "if" . showParen True (shows e1) . 
-                          sBrack b1 . shows b2
-
-instance Show (Elses t) where
-  showsPrec p elses = case elses of
-    Elseif e b els  -> showString "else" . sBrack b . shows els
-    Else b          -> showString "else" . sBrack b
-    NoElse          -> id 
-
-
-sBrack s  = showString "{" . shows s . showString "}"
-sSpace    = showString " "
-sEq       = showString " = "
-sDot      = showString "." 
-sc        = showString ";"  
-sNl       = showString "\n"
-sJtr s   = showString "'" . showString s . showString "'"
-sMaybe Nothing  = id
-sMaybe (Just s) = showString s
-
-
--------------------------------------------------------------------
--- JavaScript block representation
--------------------------------------------------------------------
-data Block t where
-  EmptyBlock  :: Block ()
-  Sequence    :: Block () -> Stmt t -> Block t
-
-instance Show (Block t) where
-  showsPrec p block = case block of
-    EmptyBlock      -> id
-    Sequence b stm  -> shows b . shows stm . sc
-    
--------------------------------------------------------------------
--- Parameters and functions
--------------------------------------------------------------------
-
--- | Class for parameter types to JavaScript functions
-class ParamType t
-
--- | Instanses for tuples,triples etc..
-instance ParamType ()
-instance JType t => ParamType t
-instance (JType t1, JType t2 ) => ParamType (t1,t2)
-instance (JType t1, JType t2, JType t3 ) => ParamType (t1,t2,t3)
-instance (JType t1, JType t2, JType t3, JType t4) => ParamType (t1,t2,t3,t4)
-instance (JType t1, JType t2, JType t3, JType t4, JType t5) => ParamType (t1,t2,t3,t4,t5)
-
-
--- | JFormal params represents parameters passed to a function along with their
--- corresponding types.
-class (Show a , ParamType t) => FormalParams a t | a -> t where
-  mkFParams :: forall b. (a -> b) -> a
-  showsFParams :: a -> ShowS
-
-instance FormalParams () () where
-  mkFParams _ = ()
-  showsFParams = shows  
-
-instance ParamType t => FormalParams (Var t) t where
-  mkFParams _ = (JParam 0)  
-  showsFParams = showParen True . shows
-
-
-instance (ParamType (t1,t2)) => FormalParams (Var t1, Var t2) (t1,t2) where
-  mkFParams _ = (JParam 0, JParam 1)
-  showsFParams = shows
-
-instance (ParamType (t1,t2,t3)) => FormalParams (Var t1, Var t2, Var t3) (t1,t2,t3) where
-  mkFParams _ = (JParam 0, JParam 1, JParam 2)
-  showsFParams = shows   
-
-
-instance (ParamType (t1,t2,t3,t4)) => FormalParams (Var t1, Var t2, Var t3, Var t4) (t1,t2,t3,t4) where
-  mkFParams _ = (JParam 0, JParam 1, JParam 2, JParam 3)
-  showsFParams = shows   
-
-instance (ParamType (t1,t2,t3,t4,t5)) => FormalParams (Var t1, Var t2, Var t3, Var t4, Var t5) (t1,t2,t3,t4,t5) where
-  mkFParams _ = (JParam 0, JParam 1, JParam 2, JParam 3, JParam 4)
-  showsFParams = shows   
-
-
--- | Args represents types that can be passed as arguments to
--- JavaScript functions.
-class Show e => Args e t | e -> t where
-  showsArgs :: e -> ShowS
-
-instance Args () () where
-  showsArgs = shows
-  
-instance Args (Exp t) t where
-  showsArgs = showParen True . shows
-
-instance  Args (Exp t1, Exp t2) (t1,t2) where
-  showsArgs = shows
-  
-instance Args (Exp t1, Exp t2, Exp t3) (t1,t2,t3) where
-  showsArgs = shows
-
-instance Args (Exp t1, Exp t2, Exp t3, Exp t4) (t1,t2,t3,t4) where
-  showsArgs = shows
-
-instance Args (Exp t1, Exp t2, Exp t3, Exp t4, Exp t5) (t1,t2,t3,t4,t5) where
-  showsArgs = shows
-
-
-
---------------------------------------------------------------------
--- Object representation
--------------------------------------------------------------------
--- Class for representing 'class' elements in javascript (e.g. Math)
-class Show c => IsClass c
-
--- | Class for binding objects with constructors. E.g. o = new Date();
-class (IsClass c, Args e t) => HasConstructor c e t
-
--- | Class for derefable data types, used to allow the creation of 
--- dereferencing objects. Examples: Math.random() or document.write()
-class Show r => IsDeref r
-
--- There are two kinds of dereferencing; either from classes or objects.
-instance IsClass c  => IsDeref c
-instance IsClass c  => IsDeref (Exp c)
-
--------------------------------------------------------------------
--- | Class for representing expressions.
--- First parameter is the expression, second a TBool for variable or constant.
--- Third parameter represents the type.
--------------------------------------------------------------------
-
-class IsExp e t | e -> t where
-  toExp :: e -> Exp t
-
-instance IsExp (Exp t) t where
-  toExp = id
-
-instance IsExp String String where
-  toExp = JString
-
-instance IsExp Int Int where
-  toExp = JInt
-
-instance IsExp Float Float where
-  toExp = JFloat
-
-instance IsExp Bool Bool where
-  toExp = JBool
-
-
--- | Class for JString expressions
-class IsExp e String => IsJString e where
-  toJString :: e -> Exp String
-  toJString = toExp
-  
--- | Class for JInt expressions
-class IsExp e Int => IsJInt e where
-  toJInt :: e -> Exp Int
-  toJInt = toExp
-  
--- | Class for JFloat expressions
-class IsExp e Float => IsJFloat e where
-  toJFloat :: e -> Exp Float
-  toJFloat = toExp
-  
-
--- | Class for JBool expressions
-class IsExp e Bool => IsJBool e where
-  toJBool :: e -> Exp Bool
-  toJBool = toExp
-
-
-instance IsExp e String => IsJString e
-
-instance IsExp e Int => IsJInt e
-
-instance IsExp e Float => IsJFloat e
-
-instance IsExp e Bool => IsJBool e
-
--------------------------------------------------------------------
--- Array
--------------------------------------------------------------------
--- | Array representation
-data Array t = Array deriving Show
-instance IsClass (Array t)
-
--------------------------------------------------------------------
--- Helper functions
--------------------------------------------------------------------
-
--- Dereferencing
-deref str obj = JDeref obj str
-
-derefVar str obj = JDerefVar obj str
-
--- Method call returning an expression.
-methodCall :: (Args e t1, IsDeref d) => String -> e -> d -> Exp t2
-methodCall fun args obj = JCall (JDeref obj fun) args
-
--- Method call for void methods. Returns a Stmt since the return value is
--- not of any interest.
-voidMethodCall :: (Args e t1, IsDeref a) => String -> e -> a -> Stmt ()
-voidMethodCall fun args = ExpStmt . methodCall fun args
-
--- Method call for functions without input parameters. Just adds the extra
--- dummy argument ().
-methodCallNoArgs ::IsDeref d => String -> d -> Exp t
-methodCallNoArgs name = methodCall name ()
-
--- Method call for functions without input parameters returning void.
-voidMethodCallNoArgs ::IsDeref d => String  -> d -> Stmt ()
-voidMethodCallNoArgs name = ExpStmt . methodCall name ()
-
-
--- | Generates a Block from a Stmt.
-toBlock :: Stmt t -> Block t
-toBlock stm = Sequence EmptyBlock stm
-
-
--- | Get the value of a variable.
-val :: Var t -> Exp t
-val = JValueOf
diff --git a/src/Language/HJavaScript/Syntax.hs b/src/Language/HJavaScript/Syntax.hs
new file mode 100644
--- /dev/null
+++ b/src/Language/HJavaScript/Syntax.hs
@@ -0,0 +1,596 @@
+{-# OPTIONS_GHC -fglasgow-exts #-}
+{-# OPTIONS_GHC -fallow-overlapping-instances #-}
+{-# OPTIONS_GHC -fallow-undecidable-instances #-}
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  Language.HJavaScript.Syntax
+-- Copyright   :  (c) Joel Bjornson 2008
+-- License     :  BSD-style
+-- Maintainer  :  Joel Bjornson joel.bjornson@gmail.com
+--                Niklas Broberg nibro@cs.chalmers.se
+-- Stability   :  experimental
+-----------------------------------------------------------------------------
+module Language.HJavaScript.Syntax
+  (
+    -- * Primitive type classes.
+    JType,
+        
+    -- * Fundamental data types.
+    Exp(..),
+    Rec,
+    Var(..),
+    Stmt(..),
+    Block(..),
+    
+    -- * Data types and classes for object representation.
+    IsClass,
+    HasConstructor,
+    IsDeref,
+    
+    -- * Misc
+    AssignOp(..),
+    BinOp(..),
+    PlusOpType,    
+    PostPre(..),
+    Elses(..),
+    IsNullable,
+    IsFeature,
+    JShow(..),
+     
+    -- * Types for functions and parameters.
+    Args,
+    ParamType,
+    FormalParams(..),
+    VarsToExps(..),
+        
+    -- * Array representation.
+    Array(..),
+       
+    -- * Type synonyms.
+    JInt, JString, JBool, JFloat, JVoid, JObject, JArray,
+    
+    -- * Type classes for expression representation.
+    IsExp(..), 
+    IsJString(..),
+    IsJBool(..),
+    IsJInt(..),
+    IsJFloat(..),
+    
+    -- * Helper functions
+    val, toBlock, deref, derefVar, 
+    call, methodCall, voidMethodCall, 
+    methodCallNoArgs, voidMethodCallNoArgs
+     
+  ) where
+   
+import Data.Char
+import Data.Maybe
+
+-- | JavaScript types
+class JType t
+instance JType String
+instance JType Int
+instance JType Bool
+instance JType ()
+instance JType Float
+instance IsClass c => JType c
+instance (Show t1, JType t1, Show t2, JType t2) => JType (t1 -> t2)
+
+-------------------------------------------------------------------
+-- JavaScript variable and expression representation
+-------------------------------------------------------------------
+
+-- Var represents JavaScript variables.
+data Var t where
+  JVar          :: String -> Var a
+  JParam        :: String -> Var a
+  JMember       :: String -> Var a
+  JDerefVar     :: IsDeref d => d -> String -> Var a
+  JArrayIndex   :: Exp (Array t) -> Exp Int -> Var t
+
+instance Show (Var t) where
+  showsPrec p var  = case var of
+    JVar v           -> showString v
+    JParam name      -> showString name
+    JMember s        -> showString s
+    JDerefVar o v    -> shows o . sDot . showString v
+    JArrayIndex a ix ->  shows a . showString "[" . 
+                               shows ix . showString "]"
+
+
+-- We model records simply as tuples, for lack of a better record mechanism
+data Rec a b
+
+-- Exp represents JavaScript Expressions.
+data Exp t where
+  JInt         :: Int    -> Exp Int
+  JFloat       :: Float  -> Exp Float
+  JBool        :: Bool   -> Exp Bool
+  JString      :: String -> Exp String
+  JRec         :: Exp a -> Exp b -> Exp (Rec a b)
+  JFst         :: Exp (Rec a b) -> Exp a
+  JSnd         :: Exp (Rec a b) -> Exp b
+  JConst       :: String -> Exp t
+  JAssign      :: Var t -> Exp t -> Exp t
+  JAssignWith  :: Var t -> AssignOp t -> Exp t -> Exp t
+  JNeg         :: Exp t -> Exp t
+  JNot         :: Exp Bool -> Exp Bool
+  JBinOp       :: Exp t -> BinOp t r -> Exp t -> Exp r
+  JIncrement   :: Num t => PostPre -> Var t -> Exp t
+  JDecrement   :: Num t => PostPre -> Var t -> Exp t
+  JIfOp        :: Exp Bool -> Exp t -> Exp t -> Exp t
+  JCall        :: (Args e t) => Exp (t -> r) -> e -> Exp r
+  JNew         :: (Args e t,  HasConstructor c e t) => c -> e -> Exp c
+  JDeref       :: IsDeref d => d -> String -> Exp t
+  JFunction    :: FormalParams a t => Maybe String -> a -> Block r -> Exp (t -> r)
+  JThis        :: IsClass c => Exp c
+  JBlock       :: Block () -> Exp ()
+  JNull        :: IsNullable t => Exp t
+  JCastObject  :: (IsClass c1, IsClass c2) => Exp c1 -> Exp c2
+  JValueOf     :: Var t -> Exp t
+  JIsImpl      :: (IsClass c , IsFeature f) => Exp c -> f -> Exp Bool
+  JShow        :: JShow t => Exp t -> Exp String
+  
+
+-------------------------------------------------------------------
+-- | Show for Exp
+-------------------------------------------------------------------
+instance Show (Exp t) where
+  showsPrec p exp = case exp of
+    JInt n                 ->  shows n
+    JFloat f               ->  shows f
+    JBool b                ->  if b then 
+                                  showString "true" 
+                                else 
+                                  showString "false"
+    JString s              ->  sJtr s
+    JRec e1 e2             ->  showString "{fst:" . shows e1 . showString "," .
+                               showString  "snd:" . shows e2 . showString "}"
+    JFst e                 ->  shows e . showString ".fst"
+    JSnd e                 ->  shows e . showString ".snd"
+    JConst c               ->  showString c
+    JAssign e1 e2          ->  shows e1 . sEq . shows e2
+    JAssignWith e1 op e2   ->  shows e1 . shows op . shows e2
+    JNeg e                 ->  showString "-" . (showParen True $ shows e)
+    JNot e                 ->  showString "!" . (showParen True $ shows e)
+    JBinOp e1 op e2        ->  shows e1 . shows op . shows e2
+    JIncrement pp e        ->  if (pp == Pre) then 
+                                  (showString "++" . shows e) 
+                                else 
+                                  (shows e . showString "++")
+    JDecrement pp e        ->  if (pp == Pre) then 
+                                  (showString "--" . shows e) 
+                                else 
+                                  (shows e . showString "--")
+    JIfOp e1 e2 e3         ->  shows e1 . showString "?" . shows e2 . 
+                               showString ":" . shows e3
+    JCall x a2             ->  shows x . showsArgs a2
+    JNew c a               ->  showString "new" . sSpace . shows c . showsArgs a
+    JDeref o e             ->  shows o . sDot . showString e
+    JFunction n fp b       ->  showString "function" .
+                                sSpace .
+                                sMaybe n . 
+                                showsFParams fp . 
+                                sBrack b
+    JThis                  ->  showString "this"
+    JBlock b               ->  shows b
+    JNull                  ->  showString "null"
+    JIsImpl ob c           ->  shows ob . sDot . showsFeature c
+    JValueOf v             ->  shows v
+    JCastObject e          ->  shows e
+    JShow e                ->  shows e
+
+
+
+-------------------------------------------------------------------
+-- Type synonyms for Exp.
+-------------------------------------------------------------------
+type JInt       = Exp Int
+type JString    = Exp String
+type JBool      = Exp Bool
+type JFloat     = Exp Float
+type JVoid      = Exp ()
+type JObject c  = Exp c
+type JArray t   = Exp (Array t)
+
+
+-------------------------------------------------------------------
+-- Additional classes
+-------------------------------------------------------------------
+
+-- | Class for representing JavaScript "features", e.g. names of 
+-- objects or functions. Example:  window `hasFeature` "alert"
+class Show a => IsFeature a where
+  showsFeature :: a -> ShowS
+
+-- A class can be a feature
+instance IsClass c => IsFeature c where
+  showsFeature = shows
+  
+
+-- | Any string value can be a feature.
+instance IsFeature String where
+  showsFeature = showString
+
+
+-- | Class that represents showable types
+class JShow a where
+ jshow :: a -> JString
+
+instance JShow Int where
+ jshow = jshow . JInt
+
+instance JShow Float where
+ jshow = jshow . JFloat
+ 
+instance JShow Bool where
+ jshow = jshow . JBool
+ 
+instance JShow String where
+ jshow = JString
+
+instance JShow a => JShow (Exp a) where
+ jshow = JShow
+
+-- | Allows values to be compared to JNull. E.g. for checking that
+-- an object is instantiated or is accessible.
+class IsNullable a
+
+-- | All JString values along with all objects and all functions can be null.
+instance IsNullable String
+instance IsClass c => IsNullable c
+instance IsNullable (t -> r)
+
+-------------------------------------------------------------------
+-- JavaScript statements representation
+-------------------------------------------------------------------
+-- | Post or Pre prefix , i.e. --x or x++
+data PostPre = Pst | Pre deriving Eq
+
+
+-- | Assign Operator
+data AssignOp t where
+  PlusAssign  :: Num t => AssignOp t
+  MinusAssign :: Num t => AssignOp t
+  TimesAssign :: Num t => AssignOp t
+  DivAssign   :: AssignOp Float
+  ModAssign   :: AssignOp Int
+  AndAssign   :: AssignOp Bool
+  OrAssign    :: AssignOp Bool
+
+instance Show (AssignOp t) where
+  showsPrec p exp = case exp of
+    PlusAssign  -> showString "+="
+    MinusAssign -> showString "-="
+    TimesAssign -> showString "*="
+    DivAssign   -> showString "/="
+    ModAssign   -> showString "%="
+    AndAssign   -> showString "&="
+    OrAssign    -> showString "|="
+      
+
+-- | Class for expression that may be "plussed".
+-- Examples: 1 + 2, "ha" + "skell".
+class PlusOpType a 
+instance PlusOpType String
+instance PlusOpType Int
+instance PlusOpType Float
+
+-- | Binary Operator
+data BinOp t r where
+  Plus        :: PlusOpType t => BinOp t t  
+  Minus       :: Num t => BinOp t t
+  Times       :: Num t => BinOp t t
+  Div         :: Num t => BinOp t t
+  Mod         :: BinOp Int Int
+  And         :: BinOp Bool Bool
+  Or          :: BinOp Bool Bool
+  Equals      :: BinOp t Bool
+  NotEquals   :: BinOp t Bool
+  GThan       :: Num t => BinOp t Bool
+  LThan       :: Num t => BinOp t Bool
+  GEThan      :: Num t => BinOp t Bool
+  LEThan      :: Num t => BinOp t Bool
+  
+
+instance Show (BinOp t r) where
+  showsPrec p exp = case exp of
+    Plus      -> showString " + "
+    Minus     -> showString " - "
+    Times     -> showString " * "
+    Div       -> showString " / "
+    Mod       -> showString " % "
+    And       -> showString " && "
+    Or        -> showString " || "
+    Equals    -> showString " == "
+    NotEquals -> showString " != "
+    GThan     -> showString " > "
+    LThan     -> showString " < "
+    GEThan    -> showString " >= "
+    LEThan    -> showString " <= "
+    
+    
+data Stmt t where
+  VarDecl       :: String -> Stmt ()
+  VarDeclAssign :: String -> Exp t -> Stmt ()
+  VarAssign     :: String -> Exp t -> Stmt ()
+  ExpStmt       :: Exp t -> Stmt ()
+  While         :: Exp Bool -> Block () -> Stmt ()
+  DoWhile       :: Block () -> Exp Bool -> Stmt ()
+  For           :: Stmt t1 -> Exp Bool -> Exp t2 -> Block () -> Stmt ()  
+  Break         :: Stmt ()
+  Continue      :: Stmt ()
+  Return        :: Exp t -> Stmt t
+  If            :: Exp Bool -> Block t -> Elses t -> Stmt ()
+  
+data Elses t where
+  Elseif  :: Exp Bool -> Block t -> Elses t -> Elses t
+  Else    :: Block t -> Elses t
+  NoElse  :: Elses ()  
+  
+instance Show (Stmt t) where
+  showsPrec p stm = case stm of
+    VarDecl s         ->  showString "var" . sSpace . showString s
+    VarAssign s e     ->  showString s . showString " = " . shows e
+    VarDeclAssign s e ->  showString "var" . sSpace . showString s .  
+                          showString " = " . shows e 
+    ExpStmt e         ->  shows e
+    While e b         ->  showString "while" . showParen True (shows e) . 
+                          sBrack b
+    DoWhile b e       ->  showString "do" . sBrack b . showString "while" . 
+                          showParen True (shows e)
+    For e1 e2 e3 b    ->  showString "for" . 
+                          showParen True (shows e1 . sc . shows e2 . 
+                          sc . shows e3) . sBrack b
+    Break             ->  showString "break"
+    Continue          ->  showString "continue"
+    Return e          ->  showString "return" . showString " " . shows e
+    If e1 b1 b2       ->  showString "if" . showParen True (shows e1) . 
+                          sBrack b1 . shows b2
+
+instance Show (Elses t) where
+  showsPrec p elses = case elses of
+    Elseif e b els  -> showString "else" . sBrack b . shows els
+    Else b          -> showString "else" . sBrack b
+    NoElse          -> id 
+
+
+sBrack s  = showString "{" . shows s . showString "}"
+sSpace    = showString " "
+sEq       = showString " = "
+sDot      = showString "." 
+sc        = showString ";"  
+sNl       = showString "\n"
+sJtr s   = showString "'" . showString s . showString "'"
+sMaybe Nothing  = id
+sMaybe (Just s) = showString s
+
+
+-------------------------------------------------------------------
+-- JavaScript block representation
+-------------------------------------------------------------------
+data Block t where
+  EmptyBlock  :: Block ()
+  Sequence    :: Block () -> Stmt t -> Block t
+
+instance Show (Block t) where
+  showsPrec p block = case block of
+    EmptyBlock      -> id
+    Sequence b stm  -> shows b . shows stm . sc
+    
+-------------------------------------------------------------------
+-- Parameters and functions
+-------------------------------------------------------------------
+
+-- | Class for parameter types to JavaScript functions
+class ParamType t
+
+-- | Instanses for tuples,triples etc..
+instance ParamType ()
+instance JType t => ParamType t
+instance (JType t1, JType t2 ) => ParamType (t1,t2)
+instance (JType t1, JType t2, JType t3 ) => ParamType (t1,t2,t3)
+instance (JType t1, JType t2, JType t3, JType t4) => ParamType (t1,t2,t3,t4)
+instance (JType t1, JType t2, JType t3, JType t4, JType t5) => ParamType (t1,t2,t3,t4,t5)
+
+
+-- | JFormal params represents parameters passed to a function along with their
+-- corresponding types.
+class (Show a , ParamType t) => FormalParams a t | a -> t where
+  mkFParams :: forall b. (a -> b) -> Int -> a
+  showsFParams :: a -> ShowS
+
+instance FormalParams () () where
+  mkFParams _ _ = ()
+  showsFParams = shows  
+
+instance ParamType t => FormalParams (Var t) t where
+  mkFParams _ n = (JParam $ "param" ++ show n ++ "_0")  
+  showsFParams = showParen True . shows
+
+
+instance (ParamType (t1,t2)) => FormalParams (Var t1, Var t2) (t1,t2) where
+  mkFParams _ n = (JParam $ "param" ++ show n ++ "_0", JParam $ "param" ++ show n ++ "_1")
+  showsFParams = shows
+
+instance (ParamType (t1,t2,t3)) => FormalParams (Var t1, Var t2, Var t3) (t1,t2,t3) where
+  mkFParams _ n = (JParam $ "param" ++ show n ++ "_0", JParam $ "param" ++ show n ++ "_1", JParam $ "param" ++ show n ++ "_2")
+  showsFParams = shows   
+
+
+instance (ParamType (t1,t2,t3,t4)) => FormalParams (Var t1, Var t2, Var t3, Var t4) (t1,t2,t3,t4) where
+  mkFParams _ n = (JParam $ "param" ++ show n ++ "_0", JParam $ "param" ++ show n ++ "_1", 
+                    JParam $ "param" ++ show n ++ "_2", JParam $ "param" ++ show n ++ "_3")
+  showsFParams = shows   
+
+instance (ParamType (t1,t2,t3,t4,t5)) => FormalParams (Var t1, Var t2, Var t3, Var t4, Var t5) (t1,t2,t3,t4,t5) where
+  mkFParams _ n = (JParam $ "param" ++ show n ++ "_0", JParam $ "param" ++ show n ++ "_1", 
+                    JParam $ "param" ++ show n ++ "_2", JParam $ "param" ++ show n ++ "_3", 
+                    JParam $ "param" ++ show n ++ "_4")
+  showsFParams = shows   
+
+
+-- | Args represents types that can be passed as arguments to
+-- JavaScript functions.
+class Show e => Args e t | e -> t where
+  showsArgs :: e -> ShowS
+
+instance Args () () where
+  showsArgs = shows
+  
+instance Args (Exp t) t where
+  showsArgs = showParen True . shows
+
+instance  Args (Exp t1, Exp t2) (t1,t2) where
+  showsArgs = shows
+  
+instance Args (Exp t1, Exp t2, Exp t3) (t1,t2,t3) where
+  showsArgs = shows
+
+instance Args (Exp t1, Exp t2, Exp t3, Exp t4) (t1,t2,t3,t4) where
+  showsArgs = shows
+
+instance Args (Exp t1, Exp t2, Exp t3, Exp t4, Exp t5) (t1,t2,t3,t4,t5) where
+  showsArgs = shows
+
+
+class VarsToExps v e | v -> e, e -> v where
+  v2e :: v -> e
+
+instance VarsToExps () () where
+  v2e = id
+
+instance VarsToExps (Var t) (Exp t) where
+  v2e = val
+
+instance VarsToExps (Var t1, Var t2) (Exp t1, Exp t2) where
+  v2e (v1,v2) = (val v1,val v2)
+
+instance VarsToExps (Var t1, Var t2, Var t3) (Exp t1, Exp t2, Exp t3) where
+  v2e (v1,v2,v3) = (val v1,val v2,val v3)
+
+instance VarsToExps (Var t1, Var t2, Var t3, Var t4) (Exp t1, Exp t2, Exp t3, Exp t4) where
+  v2e (v1,v2,v3,v4) = (val v1,val v2,val v3,val v4)
+
+instance VarsToExps (Var t1, Var t2, Var t3, Var t4, Var t5) (Exp t1, Exp t2, Exp t3, Exp t4, Exp t5) where
+  v2e (v1,v2,v3,v4,v5) = (val v1,val v2,val v3,val v4,val v5)
+
+--------------------------------------------------------------------
+-- Object representation
+-------------------------------------------------------------------
+-- Class for representing 'class' elements in javascript (e.g. Math)
+class Show c => IsClass c
+
+-- | Class for binding objects with constructors. E.g. o = new Date();
+class (IsClass c, Args e t) => HasConstructor c e t
+
+-- | Class for derefable data types, used to allow the creation of 
+-- dereferencing objects. Examples: Math.random() or document.write()
+class Show r => IsDeref r
+
+-- There are two kinds of dereferencing; either from classes or objects.
+instance IsClass c  => IsDeref c
+instance IsClass c  => IsDeref (Exp c)
+
+-------------------------------------------------------------------
+-- | Class for representing expressions.
+-- First parameter is the expression, second a TBool for variable or constant.
+-- Third parameter represents the type.
+-------------------------------------------------------------------
+
+class IsExp e t | e -> t where
+  toExp :: e -> Exp t
+
+instance IsExp (Exp t) t where
+  toExp = id
+
+instance IsExp String String where
+  toExp = JString
+
+instance IsExp Int Int where
+  toExp = JInt
+
+instance IsExp Float Float where
+  toExp = JFloat
+
+instance IsExp Bool Bool where
+  toExp = JBool
+
+
+-- | Class for JString expressions
+class IsExp e String => IsJString e where
+  toJString :: e -> Exp String
+  toJString = toExp
+  
+-- | Class for JInt expressions
+class IsExp e Int => IsJInt e where
+  toJInt :: e -> Exp Int
+  toJInt = toExp
+  
+-- | Class for JFloat expressions
+class IsExp e Float => IsJFloat e where
+  toJFloat :: e -> Exp Float
+  toJFloat = toExp
+  
+
+-- | Class for JBool expressions
+class IsExp e Bool => IsJBool e where
+  toJBool :: e -> Exp Bool
+  toJBool = toExp
+
+
+instance IsExp e String => IsJString e
+
+instance IsExp e Int => IsJInt e
+
+instance IsExp e Float => IsJFloat e
+
+instance IsExp e Bool => IsJBool e
+
+-------------------------------------------------------------------
+-- Array
+-------------------------------------------------------------------
+-- | Array representation
+data Array t = Array deriving Show
+instance IsClass (Array t)
+
+-------------------------------------------------------------------
+-- Helper functions
+-------------------------------------------------------------------
+
+-- Dereferencing
+deref str obj = JDeref obj str
+
+derefVar str obj = JDerefVar obj str
+
+-- Calling a function
+call :: (Args e t) => Exp (t -> r) -> e -> Exp r
+call = JCall
+
+-- Method call returning an expression.
+methodCall :: (Args e t1, IsDeref d) => String -> e -> d -> Exp t2
+methodCall fun args obj = JCall (JDeref obj fun) args
+
+-- Method call for void methods. Returns a Stmt since the return value is
+-- not of any interest.
+voidMethodCall :: (Args e t1, IsDeref a) => String -> e -> a -> Stmt ()
+voidMethodCall fun args = ExpStmt . methodCall fun args
+
+-- Method call for functions without input parameters. Just adds the extra
+-- dummy argument ().
+methodCallNoArgs ::IsDeref d => String -> d -> Exp t
+methodCallNoArgs name = methodCall name ()
+
+-- Method call for functions without input parameters returning void.
+voidMethodCallNoArgs ::IsDeref d => String  -> d -> Stmt ()
+voidMethodCallNoArgs name = ExpStmt . methodCall name ()
+
+
+-- | Generates a Block from a Stmt.
+toBlock :: Stmt t -> Block t
+toBlock stm = Sequence EmptyBlock stm
+
+
+-- | Get the value of a variable.
+val :: Var t -> Exp t
+val = JValueOf