[Haskell-cafe] Looking for maintainers or comaintainers on my Haskell projects

Ben Franksen ben.franksen at online.de
Sat Mar 18 23:12:14 UTC 2017

Am 17.03.2017 um 15:27 schrieb Mario Blažević:
> On 2017-03-16 05:26 PM, Ben Franksen wrote:
>> I am glad my remark didn't scare you off, in retrospect my wording was
>> perhaps a bit strong. Yes, John did a lot to make things as lazy as
>> possible to avoid excessive memory consumption (cool to say that, isn't
>> it). There is also some ugly type casting (unsafeCoerce) going on, since
>> the parser keeps the alternatives in an array (remember that this is a
>> packrat parser).
>     I should be able to replace the array with a user-defined record, I
> submitted a paper to this year's ICFP demonstrating this.

That sounds interesting. Looking forward to read that.

> The only
> problem would be backward compatibility, but if there are no current
> users there's no problem.

>> Unfortunately I can't spare the time to work on this ATM. But I would be
>> glad if you would revive the project. PEGs offer some unique advantages
>> for day-to-day parsing tasks, where you can't be bothered to write a
>> separate lexer or mess around with 'try' until your harmless looking
>> grammar actually accepts the source language. A fair portion of these
>> can nowadays be handled nicely with regex-applicative (many file formats
>> are actually regular) but now and again there is one where you need the
>> power of a CFG.
>     We're on the same page here. I have a solution in mind that would
> allow one to choose a parsing algorithm, from Parsec-style to Packrat to
> parallel-parsing CFGs, and apply it to a single grammar specification
> written with little syntactic overhead compared to Parsec. Some of it is
> written up, some half-implemented.

My gut feeling would be so say that this can't work because they all
build on a different (though /almost/ the same) set of primitives. For
instance, IIRC the semantics of 'many' differs in subtle ways between
implementations (greedy vs. maximum munch -- but don't ask me about the
details its been a while since I studied these things).


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