gistfile1.hs

       data Expr = ScSymbol String
                   | ScString String
                   | ScNumber Integer
                   | ScDouble Double 
                   | ScCons Expr Expr
                   | ScNil
                   | ScBool Bool
                   | ScQuote Expr
            deriving Show
       
       toString :: Expr -> String
       toString (ScSymbol name) = name
       toString (ScNumber num) = show num
       toString (ScDouble num) = show num
       toString ScNil = "'()"
       toString (ScQuote exp) = "'" ++ (toString exp)
       toString (ScBool value) = if value then "#t" else "#f"
       toString (ScString str) = "\"" ++ str ++ "\""
       toString (ScCons first rest) = "(" ++ (toString first) ++ (toStringCons rest)
       toStringCons (ScCons part rest) = " " ++ (toString part) ++ toStringCons rest
       toStringCons ScNil = ")"
       toStringCons other = "." ++ (toString other) ++ ")"