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Date: Fri, 24 Aug 2007 11:14:14 +0100
From: Jeremy Yallop <jeremy.yallop@ed.ac.uk>
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To: skaller <skaller@users.sourceforge.net>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] pm variant type question
References: <1187931704.7202.9.camel@rosella.wigram>
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X-Spam: no; 0.00; regexp:01 regexp:01 seq:01 seq:01 wrote:01 caml-list:01 closure:01 closure:01 variant:02 parameter:02 string:02 string:02 epsilon:04 epsilon:04 null:05 

skaller wrote:
> type 'a regexp_t' =
>   [
>   | `REGEXP_seq of 'a regexp_t' * 'a regexp_t' (** concatenation *)
>   | `REGEXP_alt of 'a regexp_t' * 'a regexp_t' (** alternation *)
>   | `REGEXP_aster of 'a regexp_t'  (** Kleene closure *)
>   | `REGEXP_string of string   (** concatenation of chars of string *)
>   | `REGEXP_epsilon            (** epsilon: null string *)
>   ]

If I understand rightly, then this should be

   type 'a regexp_t' =
     [
     | `REGEXP_seq of 'a * 'a (** concatenation *)
     | `REGEXP_alt of 'a * 'a (** alternation *)
     | `REGEXP_aster of 'a  (** Kleene closure *)
     | `REGEXP_string of string   (** concatenation of chars of string *)
     | `REGEXP_epsilon            (** epsilon: null string *)
     ]

The version you gave will result in an xreg_t type that doesn't allow 
things like

    `REGEXP_alt (`REGEXP_code x, `REGEXP_code x)

(In fact, in your version, the 'a parameter is never actually used.)

Jeremy.