Constructions with matching

• The keyword ``function'' no longer exists. One must use only ``fun''.
• The pattern matchings, in constructions with ``fun'', ``match'' and ``try'' are closed with brackets: an open bracket ``['' before the first case, and a close bracket ``]'' after the last one:

  Ocaml	Righteous
  match e with	match e with
  p1 -> e1	[ p1 -> e1
  | p2 -> e2;;	| p2 -> e2 ];
  fun x -> x;;	fun [x -> x];

  But if there is only one case and if the pattern is irrefutable, the brackets are not required. These examples work identically in Ocaml and in righteous syntax:

  Ocaml	Righteous
  fun x -> x	fun x -> x
  fun {foo=(y, _)} -> y	fun {foo=(y, _)} -> y

  The currified pattern matching can be done with ``fun'', but only with irrefutable patterns:

  Ocaml	Righteous
  fun x (y, z) -> t	fun x (y, z) -> t
  fun x y (C z) -> t	fun x y -> fun [C z -> t]

• It is possible to write the empty function, raising the exception ``Match_failure'' whichever parameter is applied, the empty ``match'', raising ``Match_failure'' after having evaluated its expression, and the empty ``try'', equivalent to its expression without try:

      fun []
      match e with []
      try e with []
  

• The patterns after ``let'' and ``value'' must be irrefutable. The following Ocaml expression:

      let f (x::y) = ...
  

  must be written in Righteous:

      let f = fun [ [x::y] -> ...
  

• The construction ``where'' is back, but one can write only one bind: e where x = y but not: e where x = y and z = t