From: Wagner Macedo <wagnerluis1982-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: pandoc-discuss-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
Subject: Re: Towards (better) Python filters for Pandoc with fluent queries
Date: Fri, 2 Jan 2015 12:09:48 -0300 [thread overview]
Message-ID: <CAKGY2P=gf8EWB9LYJ8ERenVAH19uxtY9w9gWB+Pnx2iF0sbUTA@mail.gmail.com> (raw)
In-Reply-To: <CAJ9X=kb9W0_Jd4ufPcRiZSSZ+5Bpftg4hZ82zCuBLb-moadnSQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
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Very, very good work!
I wrote and still write a lot of pandoc filters with Python and I agree:
it's often a nightmare. I will see your effort with care!
--
Wagner Macedo
On 2 January 2015 at 03:58, Elliott Slaughter <elliottslaughter-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> I like being able to script Pandoc via filters in Python, but one of the
> major drawbacks of the approach as it currently stands is that Python has
> no pattern matching to speak of. As a result, code that needs to run
> queries of the structure of Pandoc documents quickly turns into a
> nightmare, especially if that code needs to check nested structures.
>
> Consider the following partial function in Haskell, which matches against
> a BlockQuote containing a Para where the first word is "Chapter" in small
> caps:
>
> filter :: Block -> Block
> filter (BlockQuote [Para (SmallCaps [Str "Chapter"]):_]) = ...
>
> Without pattern matching, the equivalent code in Python is painful to
> write, opaque, and quite brittle. Unfortunately, without support for
> pattern matching, there is no possibility of a direct analogue in Python.
> Instead, I propose a fluent interface
> <https://en.wikipedia.org/wiki/Fluent_interface> as a way to provide a
> query language of sorts for Python. So for example, the same query might
> look like:
>
> m = Matcher(block).
> BlockQuote(length = 1)[0].
> Para(length = -1)[0].
> SmallCaps(length = 1)[0].
> Str(content = 'Chapter')
> if m.matches():
> ...
>
> The code is not quite as dense because I've split it out for legibility,
> but can be condensed better to fit on a single line if desired. It is at
> any rate a massive improvement over hand-written queries over the JSON
> structure of the document.
>
> A proof of concept library is available today, and has been demonstrated
> with the query above as well as other queries I have needed in my own
> projects. Current coverage of the Pandoc API is at around 50%. The code is
> made available under an MIT license:
>
> https://bitbucket.org/elliottslaughter/pandocpatterns
>
> I would greatly appreciate any thoughts or feedback on the concept,
> design, or implementation. Please feel free to take the code out for a test
> drive and kick the tires. If there is interest, I would be willing to
> invest the effort to improve the library and make it more robust and useful.
>
> Thank you for your time.
>
>
> --
> Elliott Slaughter
>
> "Don't worry about what anybody else is going to do. The best way to
> predict the future is to invent it." - Alan Kay
>
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next prev parent reply other threads:[~2015-01-02 15:09 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-02 6:58 Elliott Slaughter
[not found] ` <CAJ9X=kb9W0_Jd4ufPcRiZSSZ+5Bpftg4hZ82zCuBLb-moadnSQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-02 10:34 ` Mark Szepieniec
[not found] ` <CAE4-1rVjgCKdkXWOVkmyiwhDxxDawLHaLt0qkr7nUEp0QnPQyQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-03 5:46 ` Elliott Slaughter
2015-01-02 15:09 ` Wagner Macedo [this message]
2015-01-02 16:50 ` John MacFarlane
[not found] ` <20150102165038.GA25833-bi+AKbBUZKbivNSvqvJHCtPlBySK3R6THiGdP5j34PU@public.gmane.org>
2015-01-03 5:50 ` Elliott Slaughter
[not found] ` <CAJ9X=ka-d7_rg4qSejF_ueWysg_oJ_LxYS9QHcJKgdU-Os0XHQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-03 10:17 ` Caleb McDaniel
[not found] ` <4b9fb48b-091c-44c6-9201-f5c5b559253f-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>
2015-01-04 8:23 ` Elliott Slaughter
[not found] ` <CAJ9X=kZu94RTat+SKLknvUJJQWnENd9xkF9DJCJCHhiBY-qyDA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-01-04 8:25 ` Elliott Slaughter
2015-01-22 5:25 ` Elliott Slaughter
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