Example for code blocks in Typst

code-block-example.typ

#set par(justify: true)

*Goal*: being able to add line numbers, which are correct even in case of long lines that need wrapping.

*Strategy*: duplicate the code block, once for getting the line numbers correct, and the other for syntax highlighting. The idea is to split lines and prefix each line with its line number such that line wrapping should be respected.

#show raw.where(block: true): it => { set par(justify: false); grid(
  columns: (100%, 100%),
  column-gutter: -100%,
  block(width: 100%, inset: 1em, for i, line in it.text.split("\n") {
    box(width: 0pt, align(right, str(i + 1) + h(2em)))
    hide(line)
    linebreak()
  }),
  block(radius: 1em, fill: luma(246), width: 100%, inset: 1em, it),
)}


#set text(size: 12pt)
#let code = read("config-pascal.json")
#raw(code, block:true, lang: "json")

```haskell
Bool = True | False
```

Typst syntax may have changed a little since then, so I came up with this slight variation on your original.

#show raw.where(block: true): it => {
  let i = 0
  set par(justify: false); grid(
  columns: (100%, 100%),
  column-gutter: -100%,
  block(width: 100%, inset: 1em, for line in it.text.split("\n") {
    i += 1
    box(width: 0pt, align(right, str(i) + h(2em)))
    hide(line)
    linebreak()
  }),
  block(radius: 1em, fill: luma(246), width: 100%, inset: 1em, it),
)}

This variant gave me the look I was looking for:

#show raw.where(block: true): it => {
  set text(0.9em)
  set par(justify: false)
  let i = 0
  grid(
    columns: (100%, 100%),
    column-gutter: -100%,
    block(width: 100%, for line in it.text.split("\n") {
      i += 1
      box(width: 0pt, align(right, text(size: 0.9em, fill: luma(127), str(i) + h(1.5em))))
      hide(line)
      linebreak()
    }),
    it,
  )
}

when used like this:

#figure(
  block(stroke: 0.5pt, width: 100%, inset: 5pt)[
    #set align(left)
    code here...
  ])

This belongs to a standard library. Is there anything like it in the "universe"?