(* camlp4r pa_extend.cmo q_MLast.cmo *)

(***********************************************************************)

(*                                                                     *)

(*                             Camlp4                                  *)

(*                                                                     *)

(*        Daniel de Rauglaudre, projet Cristal, INRIA Rocquencourt     *)

(*                                                                     *)

(*  Copyright 1998 Institut National de Recherche en Informatique et   *)

(*  Automatique.  Distributed only by permission.                      *)

(*                                                                     *)

(***********************************************************************)

open Pcaml;

value o2b =

  fun

  [ Some _ -> True

  | None -> False ]

;

EXTEND

  GLOBAL: expr;

  expr: LEVEL "top"

    [ [ "do"; "{"; seq = sequence; "}" ->

          match seq with

          [ [e] -> e

          | _ -> <:expr< do { $list:seq$ } >> ] ] ]

  ;

  sequence:

    [ [ "let"; o = OPT "rec"; l = LIST1 let_binding SEP "and"; [ "in" | ";" ];

        el = SELF ->

          let e =

            match el with

            [ [e] -> e

            | _ -> <:expr< do { $list:el$ } >> ]

          in

          [ <:expr< let $opt:o2b o$ $list:l$ in $e$ >> ]

      | e = expr; ";"; el = SELF ->

          let e = let _loc = MLast.loc_of_expr e in <:expr< ($e$ : unit) >> in

          [e :: el]

      | e = expr; ";" -> [e]

      | e = expr -> [e] ] ]

  ;

END;