YASnippet

YASnippet is a text markup language created in 2008 by Zhang Chiyuan.

#365on PLDB	15Years Old	3.6kUsers
0Books	0Papers	403Repos

A template system for Emacs

YASnippet website
YASnippet is developed on GitHub and has 2,476 stars
There are at least 403 YASnippet repos on GitHub
file extensions for YASnippet include yasnippet
The Google BigQuery Public Dataset GitHub snapshot shows 261 users using YASnippet in 264 repos on GitHub
GitHub supports syntax highlighting for YASnippet
HTML of this page generated by LanguagePage.ts

Example from the web:

# -*- mode: snippet -*-
# name: fun
# key: fun
# expand-env: ((yas-indent-line 'fixed))
# --
${1:function-name} :: ${2:type}
$1 ${3:arguments} $0

Example from Linguist:

# name: Read stdin
# key: stdin
# group: es6
# --
new Promise(resolve => {
	let input = "";
	process.stdin.setEncoding("UTF8");
	process.stdin.on("readable", () => {
		const chunk = process.stdin.read();
		null !== chunk ? input += chunk : resolve(input);
	})
}).then(data => {
	$1
});

Feature	Supported	Token	Example
Comments	✓		# A comment
Line Comments	✓	#	# A comment
Semantic Indentation	X

YASnippet - Text markup language

Language features