[kazinator]

I supported those parentheses in the TXR Lisp pic macro:

  1> (pic "##.#" 42)
  "42.0"
  2> (pic "(##.#)" 42)
  " 42.0 "
  3> (pic "(##.#)" -42)
  "(42.0)"

The ### notation, may be imediately preceded by a parens, which must be matched by a closing one. Both parentheses become spaces for a non-negative value, or are rendered for a negative one.

The notation is mutually exlusive with the + for requesting an explicit positive sign:

  4> (pic "(+#.#)" -42)
  "(-42.0)"
  5> (pic "(+#.#)" 42)
  "(+42.0)"

:)

The parens have become just literal text.