LaTeX writer: Use a declaration for tight lists

[jlduran]

Currently, pandoc has hard-coded the following in order to make tight lists in LaTeX:

text "\\itemsep1pt\\parskip0pt\\parsep0pt"

Which is fine, but does not allow customizations. For example, the memoir class already has a \tightlist declaration for this purpose:

\newcommand{\tightlist}{%
  \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}

I'm proposing to use a similar solution:

@@ In Writers/LaTeX.hs:
-then text "\\itemsep1pt\\parskip0pt\\parsep0pt"
+then text "\\tightlist"

@@ In templates/default.latex:
+\newcommand{\tightlist}{%
+  \setlength{\itemsep}{1pt}\setlength{\parskip}{0pt}\setlength{\parsep}{0pt}}

This allows us to customize the tightness to our needs.

Backward Compatibility

If a person is using a custom LaTeX template (not based upon the memoir class), the \tightlist declaration must be added.

[xelatihy]

This would be a great addition! I wonder if the same could be done for the horizontal rule.
I use both in my documents and have to postprocess pandoc output to fix it.

On a side note, it would also be possible to use another environment, such as compactlist/compactenum from package enumitem. But this would only work if all items of the list are compact, which I believe is what pandoc AST does.

[jiuks]

I'm getting a tightlist error when I try and convert documents now - is there some extra configuration required.

! Undefined control sequence.
l.80 \tightlist

[nkalvi]

@jiuks Are you getting this with Pandoc 1.14? It was released a few hours ago.
If the error is with 1.14, could you please provide sample source and the command line so that I can also test?

[jlduran]

@jiuks You are probably using a custom template. Pandoc now uses a \tightlist declaration that must be defined in your preamble. Try adding:

\providecommand{\tightlist}{%
  \setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}

To the preamble of your custom template.

[jiuks]

Thanks - I downloaded the default template and re-configured mine, so all now fixed.

[ghost]

This change could influence lots of customized templates by resulting in an LaTeX error:

! Undefined control sequence.
l.40 \tightlist

Since Pandoc doesn't show the specific .tex source file to be built, this kind of error comes hard to locate.

In addition, in the world of LaTeX, we don't recommend one to use this kind of tricky to define a tight list. The better way, and also the suggested way of making a tight list is to use the package enumitem as follows:

\usepackage{enumitem}
\setlist{nosep, noitemsep}

[jgm]

The advantage of the present method is that it doesn't add a
dependency on an external package, enumitem. It also gives
users the ability to customize the amount of spacing.

If you use the default template, you'll be all right.
If you're using an old, customized template, then with the
change you propose there will still be an error.

I think this issue needs more discussion, but it should be
on pandoc-discuss rather than here (where only a few people will see it).

+++ Liam Huang [Jul 22 15 23:28 ]:

This change could influent lots of customized templates by resulting in
an LaTeX error:
! Undefined control sequence.
l.40 \tightlist

Since Pandoc doesn't show the specific .tex source file to be built,
this kind of error comes hard to locate.

In addition, in the world of LaTeX, we don't recommend one to use this
kind of tricky to define a tight list. The better way, and also the
suggested way of making a tight list is to use the package enumitem as
follows:

\usepackage{enumitem}
\setlist{nosep, noitemsep}

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References

1. LaTeX writer: Use a declaration for tight lists #1571 (comment)

[jlduran]

@LiamHuang0205 looking at the source of enumitem, the current declaration of \tightlist should do exactly the same thing, without the need to include an additional package.

Also remember that pandoc differentiates between loose and compact lists. Wouldn't the use of your suggestion affect both types of lists?