The template syntax is actually from go[0] which you can find some guides[1] for. While the Hugo website now mentions this, I'm not sure it always made it clear the syntax is not its own (it just seems to be frustratingly light on some use-cases). Once you understand the syntax though, it applies to more than just Hugo.

[0]: https://golang.org/pkg/text/template/ [1]: https://gowebexamples.com/templates/