EML is a simple templating language that lets you generate text with plain OCaml.
The syntax is as follow :

First of all, you need to declare the template's arguments at the top of the template :

<%# arg1 (arg2:type) (arg3_1, arg3_2) %>

The you can use two tags :

<% ocaml code here %>

This tag expect any ocaml code. If what you put in here is an expression of type unit, you should include the ";" yourself.
You are able to open parenthesis and close them in a subsequent tag.

<%- ocaml expression here %>

This tag expect an expression of type string and is going to be replaced by the value of the expression.
If this tag is inside a loop or an if statement, it's going to behave you would expect it to.

Because OCaml does not have an eval function, the templates have to be compiled.
What is provided by this package is an executable that will compile either a single .eml file into an OCaml module containing a function that render the template, or take a whole directory containing a function for each .eml file and a submodule for each subdirectory (it's recursive).

Here is an exemple of a dune rule:

(rule
 (target templates.ml)
 (deps (source_tree templates))
 (action (run eml_compiler templates)))