>
> when I type
> value x ~num(num=3) y = num > 0 ;
>
--> value x: ~?num:int -> bool
>
> However, the signature can not be parsed by Camlp4

however, I tried parse_sig "value x : ?num:int -> bool ;", it's ok,
>

This seems to be a bug in the printer.
(By the way, it is not useful to declare an optional argument as last
parameter of a function, because it cannot be erased. You will have to pass
it explicitely (otherwise caml couldn't make the difference between writing
the function and writing the function application, writing (x ~num:None) to
get the default value).

 module X : sig type a = int; and b = (int * int); end
> you can see the semi is redudant, it is an error?
>

Again, this looks like a printer issue. The correct syntax has no semicolon
before "and":  (type .. and .. and ...) is a single phrase.

For a relatively comprehensive documentation of the revised syntax¹, see
  http://caml.inria.fr/pub/docs/tutorial-camlp4/tutorial005.html
(This is the revised syntax as of camlp4 < 3.10, and possibly Camlp5; in
current versions of Camlp4 I think the rules have been slightly relaxed, but
that it is backward-compatible.)

2011/5/9 bob zhang <bobzhang1988@gmail.com>

> Hi, all,
> I am not sure that I made a mistake or two minor bugs in camlp4 revised
> syntax?
>
> Both cases are in toploop, after I type
>
> #camlp4r;;
> #load "camlp4rf.cma";
> Register.loaded_modules;
> - : ref (list string) =
> {Pervasives.contents=
> ["Camlp4ListComprenhsion"; "Camlp4MacroParser"; "Camlp4MacroParser";
> "Camlp4GrammarParser"; "Camlp4OCamlRevisedParserParser";
> "Camlp4QuotationExpander"; "Camlp4OCamlRevisedParser"]}
>
>
> case1:
> for the signature parsing,
>
> when I type
> value x ~num(num=3) y = num > 0 ;
> --> value x: ~?num:int -> bool
>
> However, the signature can not be parsed by Camlp4
> value parse_sig = Camlp4.PreCast.Syntax.(Gram.parse_string sig_item
> Loc.ghost);
>
> parse_sig "value x : ~?num:int -> bool;" will raie an exception
> however, I tried parse_sig "value x : ?num:int -> bool ;", it's ok,
>
> - : Camlp4.PreCast.Syntax.Ast.sig_item =
> Camlp4.PreCast.Syntax.Ast.SgVal <abstr> "x"
> (Camlp4.PreCast.Syntax.Ast.TyArr <abstr>
> (Camlp4.PreCast.Syntax.Ast.TyOlb <abstr> "num"
> (Camlp4.PreCast.Syntax.Ast.TyId <abstr>
> (Camlp4.PreCast.Syntax.Ast.IdLid <abstr> "int")))
> (Camlp4.PreCast.Syntax.Ast.TyId <abstr>
> (Camlp4.PreCast.Syntax.Ast.IdLid <abstr> "bool")))
> case 2:
> when I type
> module X = struct type a = int and b = (int * int); end;
> in the toploop
> module X : sig type a = int; and b = (int * int); end
> you can see the semi is redudant, it is an error?
>
> I thought Camlp4 was heavily used in bootstrapping itself, did I make
> some stupid assumptions??
>
> Thanks
>
>
>
>
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>