There’s `s-format` and `s-format-lex` which can even pick up variables from the current lexical scope, that is so boss! 
– Fuco1 2019-02-04 11:03 UTC
Hey just wanted to let you know there is a package called mustache.el (https://github.com/Wilfred/mustache.el) this uses a very similar syntax as your engine.
But it is a bit more complex to setup. Perhaps worth a journey, or maybe too obtuse. Just thought I would mention it because it made developing html pages a lot easier for me.
– Zimmy 2019-02-04 20:55 UTC
Wow, thanks to both of you! I didn’t know about either. s-format looks really nice, and its from Magnar Sveen, so it’s good quality (and more general than my simple thing). Mustache.el seems to be an Elisp port of mustache.js, so it has a much bigger scope and is aimed at html templating. Good to know about both, though.
– Marcin Borkowski 2019-02-10 11:26 UTC