definition module while

:: Then = Then
:: Else = Else
:: Do = Do
:: WhileExpr
	= (=.) infix 1 String WhileInt
	| If WhileBool Then WhileExpr Else WhileExpr
	| (:.) infixr 0 WhileExpr WhileExpr
	| While WhileBool Do WhileExpr
	| Skip
	| E.e: WExpr e & eval e

:: WhileBool
	= Bool Bool
	| (==.) infix 4 WhileInt WhileInt
	| (&.) infix 3 WhileBool WhileBool
	| Not WhileBool
	| E.e: WBool e & evalb e

:: WhileInt
	= Int Int
	| Var String
	| (+.) infixl 6 WhileInt WhileInt
	| E.e: WInt e & evali e

class gamma g
where
	put :: g String Int -> g
	get :: g String -> Int
instance gamma Gamma

:: Gamma
emptyGamma :: Gamma

class eval  m :: m -> (g -> g)    | gamma g
class evali m :: m -> (g -> Int)  | gamma g
class evalb m :: m -> (g -> Bool) | gamma g

instance eval WhileExpr
instance evali WhileInt
instance evalb WhileBool