parseBool :: Parser LispVal
parseBool = do c <- choice $ map char "tf"
               return $ case c of
                          't' -> Bool True
                          'f' -> Bool False
parseBool :: Parser LispVal
parseBool = do c <- choice $ map char "tf"
               return $ case c of
                          't' -> Bool True
                          'f' -> Bool False
parseBool = do c <- choice $ map char "tf"
               return $ case c of
                          't' -> Bool True
                          'f' -> Bool False