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Contributing Languages Examples

Some contributors guidelines on adding new languages examples.

Table of Contents


Ideally, the honour/burdern of providing an example would naturally go to creator of its langDef, or to its current maintanier. But since over a hundred syntax definitions have been contributed in the course of over 15 years, the original creators of a langDef might no longer be actively maintaining them.

Therefore, anyone fluent in a given language can contribute an example file for it, by either creating it from scratch or picking some third party code. Here follow some general guidelines on examples criteria.

Examples’ Goals

Beside offering a quick preview of how a language can be colorized by Highlight, examples files should also serve the following purposes:

These users don’t necessarily know the language, so the example should be representative of how real code in that language looks like and cover the various syntax elements defined in its langDef.

The same theme will produce quite different results with different languages, depending on which syntax elements are dominant, present or absent, and which elements are more commonly associated to each other — i.e. each language will have a different distribution of the colors in the scheme.

For these reasons, it’s important that an example provided a realistic preview of its language, and doesn’t omit any of its syntax elements, so that it can offer a reliable theme preview.

Needless to say, providing an example that is short and at the same time covers all the syntax elements is an art.

Adding Example Files

All examples sources are stored in the ex-src/ folder. This folder should contain only the examples files, so that Highlight GUI (or a script) can blindly import all its contents without any non-examples files creeping in.

Naming Convention

The preferred naming convention is <lang-name.lang-ext>, where lang-name is the name of its langDef, and lang-ext is the preferred extension registered in Highlight for that language.

Example: python.py

The idea is to make the example files usable in automated scripts by knowing the language’s name and it’s extension.

Also, there should be only one example per language, unless the language justifies creating a second example — for example, embeddable languages like PHP might benefit from a pure PHP code example plus an example of PHP embedded in HTML. In such cases, you’ll have to resort to filenames and extensions that make sense in that context.

Commit Checklist

Before committing a new example, you should check if you need to update the Git configuration files in this folder:

These are used to control at a local level EOL normalization and exclusion patterns, to prevent cluttering the project’s main config files.

These control end-of-lines normalization and exclusion patterns, to ensure cross-platformness of the files and keep out of the project unwanted files generated by working tools. These Git configuration files are kept local to this directory for both practical reasons and to avoid cluttering the project’s main settings files.

If your example source requires a specific EOL normalization (i.e. LF or CRLF), you should add its extension to the .gitignore file, to ensure that it will be editable on all OSs without problems.

If the editor/IDE you use to work on the example creates some configuration files, just add their extensions to the .gitignore file so that you can keep working without having to worry about unrelated files creeping into your commit.

Using Third Party Code

Custom designed examples are preferable to third party code snippets because rarely you’ll find some real code examples meeting the criteria mentioned in these guidelines.

Nevertheless, if you do find third party code that you deem fit to use, and you’d like to add it as an example, you must make sure that:

Having said that, having an example that doesn’t meet all the criteria is better than having no example at all, and a better example can always be added later on; so, adding examples from third party code is fine — especially if you come across a file intended as an example of that language or (even better) for testing a syntax highlighter.

Indeed, it would be of great help if contributors could find some nice examples to cover the languages which currently don’t have one. At the end of this document you’ll find some links to code examples resources.

Examples Guidelines

Here is a list resuming the guidelines for designing a custom example.

These are guidelines, not rules set in stone. If you think that it would make more sense to take a different approach for a given example, go ahead.

Adding the Example to the HTML Preview Doc

Once you’ve added your example source file to ex-src/, you should consider adding it to the Examples HTML Preview document by editing its AsciiDoc source file:

If you don’t know AsciiDoc, looking at how the other language examples are structured in the document should be enough to get you going. Otherwise, consult AsciiDoctor’s documentation.

Customizing Examples in HTML Preview Doc

Per-Language Custom Themes

The stylesheets of Highlight_Examples.html provide a default theme for Highlight code blocks, but also provides (and allows) some language specific themes.

In the _sass/ folder you’ll find all the tools and examples to customize the color theme of your example by adding a custom stylesheet for that specific language. For a practical example, look at:

The Sass (SCSS) files provide some ready-to-use font family settings, color schemes and palettes to simplify the task.

Font Ligatures Support

Also, if the language of your example supports well font ligatures, you can enable the Fira Code font for that language by adding to _fonts-ligatures.scss:

// Change 'your-lang' with the lang of your example:
@include FiraCodeLigatures(your-lang);

Ligatures provide a better and more elegant code reading experience. The Fira Code web font is loaded by the CSS from internet, so end users don’t need to have it installed locally to preview it.

To test ligatures support for a given language, you can use the outhtml_ligature_fonts.lua plugin in Highlight GUI.

External Resources

Here are some links to collections of code examples in various languages. The links are intended mainly as a source of inspiration. Not all of these examples collections have clear license terms, or permissive licenses, so please don’t include here any examples from them unless you’ve verified the license of the individual examples.

Code editors syntax test files:

Syntax highlighters test files:

Code examples collections:

Some “Hello World” collections: