Re: [Caml-list] Camlp4-free implementation of stream parsers (was camlp4 & OCaml 4.08)

[Daniil Baturin <daniil@baturin.org>]

Hi Jocelyn,

I've completed the first version of my project, so now I can start
looking into this again!

There's a third option: parser combinators like angstrom.
My experience with Menhir is very positive though. After initial
struggle, I came to like its new incremental API and declarative error
reporting.

Here's my parser for an extended BNF:
Menhir grammar:
https://github.com/dmbaturin/bnfgen/blob/master/src/bnf_parser.mly
Parser driver that feeds it tokens:
https://github.com/dmbaturin/bnfgen/blob/master/src/parse_bnf.ml
Error messages:
https://github.com/dmbaturin/bnfgen/blob/master/src/bnf_parser.messages
Error message module build:
https://github.com/dmbaturin/bnfgen/blob/master/src/dune#L6-L8

On 7/24/19 10:10 PM, Jocelyn Sérot wrote:
> Hi Daniil (and everyone interested by the subject),
>
> Did you have a closer look at this ? 
>
> I’m still hesitating between these three approaches for replacing the implementation of the small arithm expression parser used in Lascar [1] :
>
> i. rewrite it using the basic fns provided by the Stream library (pro: no additionnal dependency, cons: not so trivial..)
>
> ii. replace camlp4 by camlp5 (pro: straightforward, cons: long term maintainability of camlp5 (?)) 
>
> iii. rewrite it using ocamlex/menhir and embed it in the main code (pro: « standard » soon; cons: a bit heavy)
>
> Jocelyn
>
> [1] https://github.com/jserot/lascar/blob/master/src/lib/fsm_expr.ml, lines 70–112
>
> Le 2 juil. 2019 à 11:25, Daniil Baturin <daniil@baturin.org> a écrit :
>
>> Hi Jocelyn,
>> Camlp5 is still sort of maintained, but I don't think it's going to be
>> developed beyond compatibility updates.
>> For syntax extensions, everyone is switching to PPX.
>>
>> From a quick look, it seems like the only bit of camlp4 you use is
>> stream expressions.
>> This is one of the things PPX can't do (on purpose, since it doesn't
>> allow _arbitrary_ extensions),
>> but I don't think just using streams directly is going to make code much
>> longer.
>>
>> Or I missed some other camlp4 bits?
>>
>> I'm ready to work on a patch if you are open to it.
>>
>> On 7/2/19 1:44 PM, Jocelyn Sérot wrote:
>>> Le 29 juin 2019 à 17:15, Daniil Baturin <daniil@baturin.org> a écrit :
>>>
>>>> Perhaps we should make some coordinated effort to help them.
>>>> I've just sent a pull request to the ocamldot maintainer that enables
>>>> the graphviz files parsing and printing modules
>>>> to build and work with 4.08. The GTK parts have their own issues.
>>>> Next I'm going to look into LASCAR/RFSM (packages that interest me first ;).
>>>>
>>> Hi Daniil,
>>>
>>> I’ve been been thinking of removing the dependency of Lascar and RFSM on camlp4 for a while.
>>> Is switching to CamlP5 a good alternative ? 
>>>
>>> Jocelyn
>>>
>>>
>>