Show rules

You can fully override the appearance of an element using show rules. They work similarly to Typst's own show rules, but use elembic rules.

A show rule has the form e.show_(element or filter, it => replacement), where you specify the element which should be visually replaced, and then pass a function which receives the replaced element and returns the replacement.

In this function, use e.fields(it) to retrieve the replaced element's final field values. This can be used to decide what to replace the element by based on its fields, or to display some fields for debugging and so on.

For example, here's a show rule that would display the width field alongside each container.

#import "@preview/elembic:1.1.0" as e
#import "@preview/container-package:0.0.1": container

#show: e.show_(container, it => {
  let fields = e.fields(it)
  [Here's a container with width #fields.width: #it]
})

// This will display:
// "Here's a container with width 1cm: Hello world!"
#container(width: 1cm)[Hello world!]

Conditional show rules

You can also only apply show rules to elements with certain values for fields with filters. For example, you may want to remove all containers with a red or blue fill property. For this, you can use the simplest filters, which just compare field values: with filters, akin to Typst elements' where filters. Here's how you'd use them:

#import "@preview/elembic:1.1.0" as e
#import "@preview/container-package:0.0.1": container

// Remove red and blue fill containers
#show: e.show_(container.with(fill: red), none)
#show: e.show_(container.with(fill: blue), none)

// This container is removed.
#container(fill: red)[Hello world!]
// This container is also removed.
#container(fill: blue)[Hello world!]

// But this container is kept (fill isn't red or blue).
#container(fill: yellow)[Hello world!]

For more information on filters, see the dedicated chapter. They can be much more advanced and allow more fine-grained selections of elements.