Support dynamic languages in front matter (#8381)

changelog_unreleased/html/pr-8381.md

@@ -0,0 +1,31 @@
+#### Support front matter with dynamic language ([#8381](https://github.com/prettier/prettier/pull/8381) by [@fisker](https://github.com/fisker))
+
+Support [dynamic language detection](https://github.com/jonschlinkert/gray-matter#optionslanguage) in front matter, also available for `css`, `less`, `scss`, and `markdown` parser.
+
+<!-- prettier-ignore -->
+```html
+<!-- Input -->
+---my-awsome-language
+title: Title
+description: Description
+---
+  <h1>
+    prettier</h1>
+
+<!-- Prettier stable -->
+---my-awsome-language title: Title description: Description ---
+
+<h1>
+  prettier
+</h1>
+
+<!-- Prettier master -->
+---my-awsome-language
+title: Title
+description: Description
+---
+
+<h1>
+  prettier
+</h1>
+```