[Caml-list] menhir types cannot be open polymorphic variant

[Caml-list] menhir types cannot be open polymorphic variant

[Ashish Agarwal]

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$ cat parser.mly
%token INT
%start <[> `Got_int]> main
%%
main: INT {`Got_int}

$ menhir parser.mly
File "parser.mly", line 2, characters 11-11:
Error: unexpected character(s).

If I make the type exact [`Got_int], it works fine. Is there any way to get
around this? I need an open type.

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Re: [Caml-list] menhir types cannot be open polymorphic variant

[Gabriel Scherer]

Workaround 1: in another file (this won't work in the menhir header)

  type 'a start = [> `Got_int ] as 'a

then use ('a start) instead of [> `Got_int ].

Workaround 2: apply the patch below to the most recent menhir sources

diff -ru menhir-20130911.old/src/lexer.mll menhir-20130911.new/src/lexer.mll
--- menhir-20130911.old/src/lexer.mll    2013-09-11 08:58:39.000000000 +0200
+++ menhir-20130911.new/src/lexer.mll    2014-02-13 23:05:19.240180035 +0100
@@ -344,7 +344,7 @@
    of O'Caml variant types, but we ignore that possibility for the moment. *)

 and ocamltype openingpos = parse
-| "->"
+| "->" | "[>"
     { ocamltype openingpos lexbuf }
 | '>'
     { OCAMLTYPE (Stretch.Declared (mk_stretch true openingpos
(lexeme_start_p lexbuf) [])) }

On Thu, Feb 13, 2014 at 9:55 PM, Ashish Agarwal <agarwal1975@gmail.com> wrote:
> $ cat parser.mly
> %token INT
> %start <[> `Got_int]> main
> %%
> main: INT {`Got_int}
>
> $ menhir parser.mly
> File "parser.mly", line 2, characters 11-11:
> Error: unexpected character(s).
>
> If I make the type exact [`Got_int], it works fine. Is there any way to get
> around this? I need an open type.
>

Re: [Caml-list] menhir types cannot be open polymorphic variant

[Francois Pottier]

Thanks for reporting this and thanks to Gabriel for the patch suggestion.
This will be fixed in the next release of Menhir.

-- 
François Pottier
Francois.Pottier@inria.fr
http://gallium.inria.fr/~fpottier/

Re: [Caml-list] menhir types cannot be open polymorphic variant

[Ashish Agarwal]

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Thanks Gabriel!


On Fri, Feb 14, 2014 at 7:20 AM, Francois Pottier <Francois.Pottier@inria.fr
> wrote:

>
> Thanks for reporting this and thanks to Gabriel for the patch suggestion.
> This will be fixed in the next release of Menhir.
>
> --
> François Pottier
> Francois.Pottier@inria.fr
> http://gallium.inria.fr/~fpottier/
>

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