Can a templating lang other than HEEx be used for LiveView?

For LiveView until Phx 1.6 there were .eex and .leex templates, both using “eex” as templating language. Now there’s .heex, which works both with “Live” and “Dead” views. While there’s no problem using e. g. with dead templates, there’s an unclosed issue regarding “Support for Phoenix 1.6 & HEEx”. Is this kind of “HEEx” support a requirement? Or? Does anyone have first-hand experience with non-dot-heex (compatible) templates for LiveView in Phx 1.6+ ?

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Another templating language can be implemented, but it’s not trivial. See the mentions about Phoenix.LiveView.Rendered in the Phoenix.LiveView.Engine docs. So someone would have to write an implementation for Slime that returns those structs (unless they went the custom EEx engine way).

Here’s a silly little DSL I wrote for LiveView that I recall actually worked. It was a challenge to try to get it working without using any macros, that’s why the result looks very interesting (awful):

(On the other hand I kind of liked that EEx DSL – the first file in the snippet – and would use it if I didn’t have live views. :D)

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I’m wondering how tricky it would be to transform other templating languages to a heex template. So one wouldn’t need to own the complete template → rendered struct code, but only the template → heex (template) transformation.

I think that’s the way slime-lang for Phoenix works already. At least for .eex. Haven’t checked under the hood though.

mhanberg/temple: An HTML DSL for Elixir and Phoenix ( is a very interesting alternative to heex. It supports LiveView as well as regular eex templating - but - with pure elixir code.

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