Editing Meta:How to contribute

== What should I (not) write? ==

=== All kinds of contributions are welcome ===

In particular, the following are excellent ways to contribute:
* '''Correct a typo''' when you spot one.
* '''Add references''' to a page.
* '''Add up to an existing page''', ''e.g.'' by filling an empty section or by adding a section. You can check the list of all [[:Category:Pages needing work|pages where some work needs to be done]].
* '''Start a new page''', even if you only write a small definition. (As French Wikipedians say, [https://fr.wikipedia.org/wiki/Fichier:%C3%89volution_de_l%27article_Pomme.ogv {{quotes|an apple is a fruit}}].) You can check the list of all [[Special:WantedPages|wanted pages]], ''i.e.'' pages that do not exist but are already linked to somewhere.

=== All {{quotes|λ-related}} topics are welcome ===

Remember from the [[Main Page|presentation]] of the λLab that the general subjects of this wiki are theory of computation, formal logic, their mathematical semantics, and the interplay of all these. Any topic related to any of these items is ''a priori'' suited to the λLab.
Also, if there's no page yet on [some broad area], it probably only means that nobody here had the time or the skills to make one. '''Be bold''' (and [[Meta:Coffee room|ask questions]]).

On a given subject, you are welcome to write any kind of (interesting) content: '''write whatever you (or a younger you) would like to have put down somewhere.'''

However, keep in mind that the material on the λLab should be of common interest:
* '''Don't use the λLab for personal notes or drafts.''' This means that the content should be of some general interest, and that the formatting should make it clear and accessible to others. 
* Don't write non-scientific content. The λLab is not meant for popularising your brand new theory on the origin of the universe.

== How to get started? ==

=== Creating or editing a page ===

To create a page, just go to the URL you would like to create, ''e.g.'' [https://www.lambda-lab.org/wiki/My_new_page https://www.lambda-lab.org/wiki/My new page]. Make sure you respect the [[#Naming conventions|naming conventions]].

To edit a page, go to this page and click on the ''Edit'' link below the title. You can also edit a section only by clicking on the ''[edit]'' link next to the section title. It is sometimes easier to edit the source code of the page instead of using MediaWiki's [https://www.mediawiki.org/wiki/Extension:VisualEditor VisualEditor], which can be done by clicking the ''Edit source'' link. Notice that there are ''protected'' pages, ''i.e.'' pages that unauthorised users cannot edit.

If you plan to spend some time modifying a page or a section, you can use [[Template:Working on page]] or [[Template:Working on section]] to display a warning for other users.

=== Generalities on MediaWiki ===

The λLab uses [https://www.mediawiki.org/ MediaWiki] (the software running Wikipedia for example). The pages are formatted according to the syntax of {{quotes|wikicode}}, a summary of which is provided below. This syntax is partly hidden when using [https://www.mediawiki.org/wiki/Extension:VisualEditor VisualEditor], which is enabled by default on the λLab.

==== Templates ====

One of its key features is ''transclusion'', allowing to insert the content of a page (usually a ''template'') into another page. To insert the content of [[Template:Example]] into the current page and pass it some arguments, the general syntax is <code><nowiki>{{Example|argument 1|argument 2|foo=named argument}}</nowiki></code>. Templates allow to extend MediaWiki's features and to store some parts of frequently used code. The most useful templates are described on the current page.

* Here is a list of <span class="plainlinks">[https://www.lambda-lab.org/wiki/Special:AllPages?namespace=10 all available templates]</span>. 
* For most templates, the page [[Template:Template name]] contains (or will contain) a documentation.

==== Categories ====

MediaWiki allows to give categories to pages. Please don't use this feature until a hierarchy of categories is set up.

=== Typesetting text ===

Text can be formatted using ''wikicode'', the markup used by MediaWiki. See MediaWiki's help pages [https://www.mediawiki.org/wiki/Help:Formatting on markup] and [https://www.mediawiki.org/wiki/Help:Links on hyperlinks]. There are additional features:
* To put text between quotes, use <code><nowiki>{{quotes|text}}</nowiki></code>. This will produce: {{quotes|text}}.

=== Typesetting math ===

To typeset math, use the templates [[Template:$|$]] (for inline math) and [[Template:$$|$$]] (for displayed math).
For example, <code><nowiki>{{$|F : \mathbf C \to \mathbf D}} and {{$$|\sum_{i{{=}}1}^{N} a_i \cdot x^i.}}</nowiki></code> produces: {{$|F : \mathbf C \to \mathbf D}} and {{$$|\sum_{i{{=}}1}^{N} a_i \cdot x^i.}}

Notice the <code><nowiki>{{=}}</nowiki></code> producing an = sign (this is needed inside template arguments).

An important remark is that '''the λLab does not run LaTeX''', but some web libraries that use LaTeX-like syntax. Hence all your preferred LaTeX commands are not available. More precisely:
* Currently, the default behaviour of [[Template:$|$]] and [[Template:$$|$$]] is that they use MediaWiki's [https://www.mediawiki.org/wiki/Extension:Math Math extension], which runs [https://www.mathjax.org/ MathJax] on server-side (and caches the result). See [https://www.mediawiki.org/wiki/Extension:Math/Syntax here] a list of available commands.
* We also have [https://katex.org/ KaTeX] installed, which is executed client-side (hence being slower) but supports more functions (see the [https://katex.org/docs/support_table support table]). If needed, KaTeX rendering can be enabled by <code><nowiki>{{$ or $$|some math...|k=1}}</nowiki></code>.

If using a template is too painful for you, we have been enabling the usual LaTeX syntax: <code>\(...\)</code> for inline math, <code>\[...\]</code> for displayed math. This is rendered through KaTeX.

This behaviour may be modified in the future if we find better options: '''please do ''only'' use syntax described here, and not MediaWiki's built-in <code><nowiki><math></nowiki></code> tags!'''

=== Definitions, Theorems, etc. (and proofs) ===

Theorems are produced with [[Template:Theorem box]]. The syntax is as follows:
<pre>
{{Theorem box
| type=lemma (or definition, or whatever you want)
| id=a unique identifier (as for a \label{...} in TeX)
| title=... (this line is optional)
| content=...
}}
</pre>
The result is as follows:
{{Theorem box
| type=lemma
| id=unique-id
| title=title
| content=Content...
}}

Proofs are produced with [[Template:Proof]]. The syntax is <code><nowiki>{{Proof|...}}</nowiki></code>. The template has an optional <code>title</code> argument, to replace the default title of the proof.

To reference to a theorem, use [[Template:Theorem ref]] as follows: <code><nowiki>{{Theorem ref|the identifier of the theorem}}</nowiki></code>. For example, see {{Theorem ref|unique-id}}. The template has an optional <code>text</code> argument, to replace the default text of the reference; for example {{Theorem ref|unique-id|text=this}} also links to the lemma above.

=== Bibliographical references ===

Bibliographical reference should be grouped in a ''References'' section at the bottom of each page. This section should consist in one or several list(s) of references:
* [Reference 1] with a comment if needed.
* [Reference 2]
* etc.
Individual references can be typeset in a BibTeX-like syntax using the following templates: [[Template:Bib Article|Bib Article]], [[Template:Bib Book|Bib Book]], [[Template:Bib InCollection|Bib InCollection]], [[Template:Bib InProceedings|Bib InProceedings]], [[Template:Bib Misc|Bib Misc]] and [[Template:Bib Thesis|Bib Thesis]]. If you think one of these templates should be improved or a similar template is missing, feel free to [[Meta:Feature requests|request it]].

In the body of a page, references can be cited with [[Template:Cite]]. A cited reference must be present in the References section.

=== Special mathematical features ===

==== Commutative diagrams ====

Commutative diagrams can be produced with <code><nowiki>{{Diagram|...}}</nowiki></code>, with [https://redgregory.notion.site/Diagrams-With-KaTeX-9166ebfa650a463dbdf67357143ebaed KaTeX's diagram syntax].

==== Proof trees ====

Proof trees can be produced in an [https://ctan.org/pkg/ebproof ebproof]-like syntax thanks to [[Template:Proof tree]]. The following example:
<pre>
{{Proof tree
| hypo \vdash F
| infer 1 \vdash G
| hypo \vdash H
| infer 2 style:(double) label:(R) \vdash G \oplus H 
}}
</pre>
produces the following result:
{{Proof tree
| hypo \vdash F
| infer 1 \vdash G
| hypo \vdash H
| infer 2 style:(double) label:(R) \vdash G \oplus H 
}}

This is an experimental feature: please [[Meta:Bugs|report bugs]] and [[Meta:Feature requests|request enhancements]]!

== What good practices should I apply? ==

=== Naming conventions ===

First, page titles should respect MediaWiki's [https://www.mediawiki.org/wiki/Manual:Page_title#Naming_restrictions naming restrictions]. In particular there are some forbidden characters, and the title should be at most 255 bytes long.

In addition:
* Page titles should be singular nouns.
* '''Don't capitalise the titles (even for the very first letter)!''' The only capitals should be in front of proper nouns (''Church-Rosser theorem'') or mathematical symbols (''W-type'').
* You can't use math commands, but Unicode is allowed if used parsimoniously. To translate TeX to Unicode, see for example [https://www.unicodeit.net/ UnicodeIt].
* If there are obvious and widespread synonyms of the page title, you can create other pages with [https://www.mediawiki.org/wiki/Help:Redirects redirects] (''e.g.'' [[lambda-calculus]] could redirect to [[λ-calculus]], or the converse).

=== Structure of a page ===

The structure of most pages should look like [[Template:Page structure]]. To start a new page with this structure, write <code><nowiki>{{subst:Page structure}}</nowiki></code> and save the page.

Of course, this is only a suggested template that will not fit some subjects. Feel free to adapt it as much as needed!

=== Use the talk pages! ===

Each page comes with its [https://www.mediawiki.org/wiki/Help:Talk_pages talk page]. You should write on the talk page:
* If you want to make significant edits to a page, to explain what you are going to do and why.
* If you disagree with something on a page.
* If you would like to make an edit but you aren't sure of it.
* If you have a question about the content of the page.
* For any other possible reason!

To start discussing:
# Go to the talk page (by clicking on the ''Discussion'' link below the page title).
# Click on the ''Add topic'' button in the top right corner.
# Don't forget to sign your messages, by adding <code><nowiki>--~~~~</nowiki></code> at the end!

=== If you need help, do look for it ===

Remember that:
* All templates will eventually be documented on their [[Template:Template name]] page.
* You can ask for specific help on the talk page of any page.
* You can ask for anything in the [[Meta:Coffee room|Coffee room]].