Templates

The deck is a Go text/template, evaluated before the Markdown is parsed. Everything the Go template language has — actions, pipelines, if, range, with, variables — works in a deck.

Data

The template’s dot holds the front matter’s keys, then the keys of its data: mapping, then the data given on the command line or in slides.yaml — each overriding the one before.

---
marp: true
title: Quarterly review
data:
  team: Platform
---

# {{ .title }}

Presented by the {{ .team }} team.

From the command line:

Generating slides

The whole body is one template, so a range that writes --- writes slides:

{{ range .releases }}
---

# {{ .version }}

{{ range .changes }}- {{ . }}
{{ end }}
{{ end }}

Page and total

{{ page }} and {{ total }} are the slide’s number and the number of slides. They are known only once the deck has been split, so they are filled in then — a generated deck counts the slides it generated.

<!-- footer: "{{ page }} / {{ total }}" -->

Include

{{ include "parts/agenda.md" }} inserts another file, relative to the deck.

Code is left alone

Fenced code blocks and inline code spans are set aside before the template runs and restored verbatim, so a slide about Go templates can show {{ .Name }} without escaping it.

Limits

Template execution has a step budget, so that a deck whose templates nest range over large data lists cannot keep the renderer busy for minutes. Past 1,048,576 steps (loop iterations and template calls, shared with the includes of one expansion) or 10 s, the deck is refused with the diagnostic template.limit instead of hanging. A step costs about 260 ns, so ordinary decks stay far below the bound. Since v0.17.1.

Turning it off

--no-template reads the deck as plain Marp: {{ is text.