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Escaped string in sexplib
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Date: -- (:)
From: Török_Edwin <edwintorok@g...>
Subject: Re: [Caml-list] Escaped string in sexplib
On 06/08/2010 09:52 PM, Hugo Ferreira wrote:
> Hello,
> 
> Markus Mottl wrote:
>> On Tue, Jun 8, 2010 at 11:44, Hugo Ferreira <hmf@inescporto.pt> wrote:
>>> I am trying to us the Sexplib library to process data.
>>> However I am having some trouble with strings.
>>> Specifically I need to save and restore strings to a file
>>> so that the escaping done during saving is "undone"
>>> when data is read back in.
>>>
>>> How can I do this? Appreciate any pointers.
>>
>> The I/O and parsing routines in the S-expression library should take
>> care of escaped strings just fine.  
> 
> My apologies but I did not explain myself correctly. The problem here is
> that I am trying to automate the conversion to string of the data
> structure read from the s-expressions. I have the following:
> 
> let string_of_experiment_data data =
>   let data = sexp_of_experiment_data data in
>   Sexplib.Sexp.to_string_hum data
> 
> The problem here is that the "to_string_hum" escapes certain characters,
> but I need to have the strings "not escaped". So my question is: is
> their any way I can tell sexplib to output a string but not escape
> it? Otherwise I will have to hand encode this stuff 8-(
> 
>> Btw., the escaping conventions are
>> absolutely identical to the ones used by OCaml.
>>
> 
> I am aware of this as it is indicated in your documentation and
> the ocaml tutorial site. I also searched for a means to "unescape"
> the result from "to_string_hum", which would also work. However
> I cannot find a String.unescape. This issue has already been pointed
> out. A possible solution would be to use the old.
> 
>  Token.eval_string
> 
> and I cannot seem to use the equivalent of the new camlp4. The
> equivalent:
> 
> open Camlp4.PreCast
> open Syntax
> let eval_string s = Camlp4.Struct.Token.Eval.string ~strict:() s
> 
> does not compile (Error: Unbound module Camlp4.PreCast).

It compiles for me if I add -I +camlp4:
ocamlc -I +camlp4 -c x.ml
or:
ocamlfind ocamlc -package camlp4.lib -c x.ml

It also links if you add -linkpkg.

Best regards,
--Edwin