How can I create a set of shared `set` and `show` rules which can be imported into a theme?

[ParaN3xus]

These two posts may help:

Why is the template function I wrote not working properly?

Basically, show will take everything below it and process it using the function you specify. For example: #show: style content is equivalent to: #style[content] Based on this rule, let’s take a look at your code. Firstly, #let theorems(doc) = [ #show: thmrules #doc ] is equivalent to: #let theorems(doc) = [ #thmrules(doc) ] So, in reality, thmrules and theorems are exactly the same. Secondly, when you call show: all, your doc (which, in this case, refers to your entire document) …

Why the definition of "show regex" doesn't work in a function?

This is because show only works on content within its scope. In your example, this scope is the interior of the __sugar() function definition. The principle of show is that it will take everything that matches its selector below and within its scope, and process it using the function you specify. So when you call __sugar(), show did nothing because there is nothing else in it’s scope. To fix this issue, you need to write another show in the scope you want. For example: #let __sugar(content) …