---
title: Use user-defined functions
vignette: >
  %\VignetteIndexEntry{use-user-defined-functions}
  %\VignetteEngine{quarto::html}
  %\VignetteEncoding{UTF-8}
knitr:
  opts_chunk:
    collapse: true
    comment: '#>'
    message: false
---

`{r2typ}` provides pretty much all Typst function, but one might want to be able to generate Typst markup for its own custom functions.

This is possible AND very simple. For example, let's say we defined a "hello" Typst function, we can "register" it to `{r2typ}` by using `typst_function()`

```{r}
library(r2typ)

# register the "hello" function
hello <- function(...) typst_function("hello", ...)
```

```{r}
#| echo: false
# this cell is here to tell r2typ/knitr to not consider current
# page a Quarto doc in order to just display raw text output.
library(knitr)
knit_print.typst_markup <- function(x, ...) {
  unclass(x)
}
registerS3method(
  "knit_print",
  "typst_markup",
  "knit_print.typst_markup"
)
```

```{r}
hello(fill = red, size = pt_(10), other_arg = "world")
```