Streams and parsers

• The streams and the stream patterns are bracketed with ``[:'' and ``:]'' instead of ``[<'' and ``>]''.
• The stream component ``terminal'' is written with a backquote instead of a quote:

  Ocaml	Righteous
  [< '1; '2; s; '3 >]	[: `1; `2; s; `3 :]

• The cases of parsers are bracketed with ``['' and ``]'', like for ``fun'', ``match'' and ``try''. If there is one case, the brackets are not mandatory:

  Ocaml	Righteous
  parser	parser
  [< 'Foo >] -> e	[ [: `Foo :] -> e
  | [< p = f >] -> f	| [: p = f :] -> f ]
  parser [< 'x >] -> x	parser [ [: `x :] -> x ]
  parser [< 'x >] -> x	parser [: `x :] -> x

• It is possible to write the empty parser raising the exception ``Stream.Failure'' whichever parameter is applied, and the empty stream matching always raising ``Stream.Failure'':

      parser []
      match e with parser []