Starting typing in Typst is easy.
You don't need packages or other weird things for most of things.

Blank line will move text to a new paragraph.

Btw, you can use any language and unicode symbols
without any problems as long as the font supports it: ßçœ̃ɛ̃ø∀αβёыა😆…

= Markup

This was a heading. Number of `=` in front of name corresponds to heading level.

== Second-level heading

Okay, let's move to _emphasis_ and *bold* text.

Markup syntax is generally similar to
`AsciiDoc` (this was `raw` for monospace text!)

You can break \
line anywhere you \
want using "\\" symbol.

Also you can use that symbol to
escape \_all the symbols you want\_,
if you don't want it to be interpreted as markup
or other special symbols.

You can write comments with `//` and `/* comment */`:
// Like this
/* Or even like
this */

```typ
Just in case you didn't read source,
this is how it is written:

// Like this
/* Or even like
this */

By the way, I'm writing it all in a _fenced code block_ with *syntax highlighting*!
```

== What else?

There are not much things in basic "markup" syntax,
but we will see much more interesting things very soon!
I hope you noticed auto-matched "smart quotes" there.

- Writing lists in a simple way is great.
- Nothing complex, start your points with `-`
  and this will become a list.
  - Indented lists are created via indentation.

+ Numbered lists start with `+` instead of `-`.
+ There is no alternative markup syntax for lists
+ So just remember `-` and `+`, all other symbols
  wouldn't work in an unintended way.
  + That is a general property of Typst's markup.
  + Unlike Markdown, there is only one way
    to write something with it.

Typst numbered lists differ from markdown-like syntax for lists. If you write them by hand, numbering is preserved:

1. Apple
1. Orange
1. Peach

I will just mention math ($a + b/c = sum_i x^i$)
is possible and quite pretty there:

$
7.32 beta +
  sum_(i=0)^nabla
    (Q_i (a_i - epsilon)) / 2
$

To learn more about math, see corresponding chapter.

Okay, let's now move to more complex things.

First of all, there are *lots of magic* in Typst.
And it major part of it is called "scripting".

To go to scripting mode, type `#` and *some function name*
after that. We will start with _something dull_:

#lorem(50)

_That *function* just generated 50 "Lorem Ipsum" words!_

#underline[functions can do everything!]

#text(orange)[L]ike #text(size: 0.8em)[Really] #sub[E]verything!

#figure(
  caption: [
    This is a screenshot from one of first theses written in Typst. \
    _All these things are written with #text(blue)[custom functions] too._
  ],
  image("../boxes.png", width: 80%)
)

In fact, you can #strong[forget] about markup
and #emph[just write] functions everywhere!

#list[
  All that markup is just a #emph[syntax sugar] over functions!
]

First, start with `#`. Then write the name.
Finally, write some parentheses and maybe something inside.

You can navigate lots of built-in functions
in #link("https://typst.app/docs/reference/")[Official Reference].

#quote(block: true, attribution: "Typst Examples Book")[
  That's right, links, quotes and lots of
  other document elements are created with functions.
]

There are _two types_ of function arguments:

+ *Positional.* Like `50` in `lorem(50)`.
  Just write them in parentheses and it will be okay.
  If you have many, use commas.
+ *Named.* Like in `#quote(attribution: "Whoever")`.
  Write the value after a name and a colon.

If argument is named, it has some _default value_.
To find out what it is, see
#link("https://typst.app/docs/reference/")[Official Typst Reference].

The most "universal" type in Typst language is *content*.
Everything you write in the document becomes content.

#[
  But you can explicitly create it with
  _scripting mode_ and *square brackets*.

  There, in square brackets, you can use any markup
  functions or whatever you want.
]

When you use `#`, you are "switching" to code mode.
When you use `[]`, you turn back:

// +-- going from markup (the default mode) to scripting for that function
// |                 +-- scripting mode: calling `text`, the last argument is markup
// |     first arg   |
// v     vvvvvvvvv   vvvv
   #rect(width: 5cm, text(red)[hello *world*])
//  ^^^^                       ^^^^^^^^^^^^^ just a markup argument for `text`
//  |
//  +-- calling `rect` in scripting mode, with two arguments: width and other content

So what are these square brackets after functions?

If you *write content right after
function, it will be passed as positional argument there*.

#quote(block: true)[
  So #text(red)[_that_] allows me to write
  _literally anything in things
  I pass to #underline[functions]!_
]

So, just to make it clear, when I write

```typ
- #text(red)[red text]
- #text([red text], red)
- #text("red text", red)
//      ^        ^
// Quotes there mean a plain string, not a content!
// This is just text.
```

It all will result in a #text([red text], red).

#set page(width: 15cm, margin: (left: 4cm, right: 4cm))

That was great, but using functions everywhere, especially
with many arguments every time is awfully cumbersome.

That's why Typst has _rules_. No, not for you, for the document.

#set par(justify: true)

And the first rule we will consider there is `set` rule.
As you see, I've just used it on `par` (which is short from paragraph)
and now all paragraphs became _justified_.

It will apply to all paragraphs after the rule,
but will work only in it's _scope_ (we will discuss them later).

#par(justify: false)[
  Of course, you can override a `set` rule.
  This rule just sets the _default value_
  of an argument of an element.
]

By the way, at first line of this snippet
I've reduced page size to make justifying more visible,
also increasing margins to add blank space on left and right.

Before we continue with rules, we should talk about length. There are several absolute length units in Typst:

#set rect(height: 1em)

#table(
  columns: 2,
  [Points], rect(width: 72pt),
  [Millimeters], rect(width: 25.4mm),
  [Centimeters], rect(width: 2.54cm),
  [Inches], rect(width: 1in),
  [Relative to font size], rect(width: 6.5em)
)

`1 em` = current font size. \
It is a very convenient unit,
so we are going to use it a lot

#set quote(block: true, attribution: [Typst Examples Book])

#quote[
  Typst is great!
]

#quote[
  The problem with quotes on the internet is
  that it is hard to verify their authenticity.
]

#set par(justify: true)
#set list(indent: 1em)
#set enum(indent: 1em)
#set page(numbering: "1")

- List item
- List item

+ Enum item
+ Enum item

= Numbering

Some of elements have a property called "numbering".
They accept so-called "numbering patterns" and
are very useful with set rules. Let's see what I mean.

#set heading(numbering: "I.1:")

= This is first level
= Another first
== Second
== Another second
=== Now third
== And second again
= Now returning to first
= These are actual romanian numerals

Advanced styling comes with another rule. The _`show` rule_.

Now please compare the source code and the output.

#show "Be careful": strong[Play]

This is a very powerful thing, sometimes even too powerful.
Be careful with it.

#show "it is holding me hostage": text(green)[I'm fine]

Wait, what? I told you "Be careful!", not "Play!".

Help, it is holding me hostage.

Show rule is a powerful thing that takes a _selector_
and what to apply to it. After that it will apply to
all elements it can find.

It may be extremely useful like that:

#show emph: set text(blue)

Now if I want to _emphasize_ something,
it will be both _emphasized_ and _blue_.
Isn't that cool?

Sometimes show rules may be confusing. They may seem very diverse, but in fact they all are quite the same! So

// actually, this is the same as
// redify = text.with(red)
// `with` creates a new function with this argument already set
#let redify(string) = text(red, string)

// and this is the same as
// framify = rect.with(stroke: orange)
#let framify(object) = rect(object, stroke: orange)

// set default color of text blue for all following text
#show: set text(blue)

Blue text.

// wrap everything into a frame
#show: framify

Framed text.

// it's the same, just creating new function that calls framify
#show: a => framify(a)

Double-framed.

// apply function to `the`
#show "the": redify
// set text color for all the headings
#show heading: set text(purple)

= Conclusion

All these rules do basically the same!

Text before
= Heading
Text after

#show heading: set block(spacing: 0.5em)

Text before
= Heading
Text after

So show rule can accept _selectors_.

There are lots of different selector types,
for example

- element functions
- strings
- regular expressions
- field filters

Let's see example of the latter:

#show heading.where(level: 1): set align(center)

= Title
== Small title

Of course, you can set align by hand,
no need to use show rules
(but they are very handy!):

#align(center)[== Centered small title]

Let's try now writing custom functions.
It is very easy, see yourself:

// "it" is a heading, we take it and output things in braces
#show heading: it => {
  // center it
  set align(center)
  // set size and weight
  set text(12pt, weight: "regular")
  // see more about blocks and boxes
  // in corresponding chapter
  block(smallcaps(it.body))
}

= Smallcaps heading

#set page(
  // Header is that small thing on top
  header: align(
    right + horizon,
    [Some header there]
  ),
  height: 12cm
)

#align(center, text(17pt)[
  *Important title*
])

#grid(
  columns: (1fr, 1fr),
  align(center)[
    Some author \
    Some Institute \
    #link("mailto:some@mail.edu")
  ],
  align(center)[
    Another author \
    Another Institute \
    #link("mailto:another@mail.edu")
  ]
)

Now let's split text into two columns:

#show: rest => columns(2, rest)

#show heading.where(
  level: 1
): it => block(width: 100%)[
  #set align(center)
  #set text(12pt, weight: "regular")
  #smallcaps(it.body)
]

#show heading.where(
  level: 2
): it => text(
  size: 11pt,
  weight: "regular",
  style: "italic",
  it.body + [.],
)

// Now let's fill it with words:

= Heading
== Small heading
#lorem(10)
== Second subchapter
#lorem(10)
= Second heading
#lorem(40)

== Second subchapter
#lorem(40)

// define a function that:
// - takes content
// - applies styling to it
// - returns the styled content
#let apply-template(body) = [
  #show heading.where(level: 1): emph
  #set heading(numbering: "1.1")
  // ...
  #body
]

// we can reduce the number of hashes needed here by using scripting mode
// same as above but we exchanged `[...]` for `{...}` to switch from markup
// into scripting mode
#let apply-template(body) = {
  show heading.where(level: 1): emph
  set heading(numbering: "1.1")
  // ...
  body
}

#import "template.typ": apply-template
#show: apply-template

// add optional named arguments
#let apply-template(body, name: "My document") = {
  show heading.where(level: 1): emph
  set heading(numbering: "1.1")

  align(center, text(name, size: 2em))

  body
}

#import "template.typ": apply-template

// `func.with(..)` applies the arguments to the function and returns the new
// function with those defaults applied
#show: apply-template.with(name: "Report")

// it is functionally the same as this
#let new-template(..args) = apply-template(name: "Report", ..args)
#show: new-template

You can use boxes to wrap anything
into text: #box(image("../tiger.jpg", height: 2em)).

Blocks will always be "separate paragraphs".
They will not fit into a text: #block(image("../tiger.jpg", height: 2em))

#box(stroke: red, inset: 1em)[Box text]
#block(stroke: red, inset: 1em)[Block text]

#rect[Block text]

@tiger shows a tiger. Tigers
are animals.

#figure(
  image("../tiger.jpg", width: 80%),
  caption: [A tiger.],
) <tiger>

They told me to write a letter to you. Here it is:

#figure(
  text(size: 5em)[I],
  caption: [I'm cool, right?],
) 

Horizontal #h(1cm) spacing.
#v(1cm)
And some vertical too!

#set rect(height: 1em)
#table(
  columns: 2,
  [Points], rect(width: 72pt),
  [Millimeters], rect(width: 25.4mm),
  [Centimeters], rect(width: 2.54cm),
  [Inches], rect(width: 1in),
)

#set rect(height: 1em)
#table(
  columns: 2,
  [Centimeters], rect(width: 2.54cm),
  [Relative to font size], rect(width: 6.5em)
)

Double font size: #box(stroke: red, baseline: 40%, height: 2em, width: 2em)

Combined: #box(rect(height: 5pt + 1em))

#(5pt + 1em).abs
#(5pt + 1em).em

This line width is 50% of available page size (without margins):

#line(length: 50%)

This line width is 50% of the box width: #box(stroke: red, width: 4em, inset: (y: 0.5em), line(length: 50%))

#rect(width: 100% - 50pt)

#(100% - 50pt).length \
#(100% - 50pt).ratio

Left #h(1fr) Right

#rect(height: 1em)[
  #h(1fr)
]

Left #h(1fr) Left-ish #h(2fr) Right

Word: #h(1fr) #box(height: 1em, stroke: red)[
  #h(2fr)
]

#set page(height: 60pt)
Hello, world!

#place(
  top + right, // place at the page right and top
  square(
    width: 20pt,
    stroke: 2pt + blue
  ),
)

#set page(height: 150pt)
#let note(where, body) = place(
  center + where,
  float: true,
  clearance: 6pt,
  rect(body),
)

#lorem(10)
#note(bottom)[Bottom 1]
#note(bottom)[Bottom 2]
#lorem(40)
#note(top)[Top]
#lorem(10)

#set page(height: 100pt)
#for i in range(16) {
  let amount = i * 4pt
  place(center, dx: amount - 32pt, dy: amount)[A]
}

#rect(inset: 0pt, move(
  dx: 6pt, dy: 6pt,
  rect(
    inset: 8pt,
    fill: white,
    stroke: black,
    [Abra cadabra]
  )
))

#scale(x: -100%)[This is mirrored.]

A#box(scale(75%)[A])A \
B#box(scale(75%, origin: bottom + left)[B])B

Hello Jane \
#hide[Hello] Joe

#set text(size: 9pt)

#let yield_cells(n) = {
  for i in range(0, n + 1) {
    for j in range(0, n + 1) {
      let product = if i * j != 0 {
        // math is used for the better look 
        if j <= i { $#{ j * i }$ } 
        else {
          // upper part of the table
          text(gray.darken(50%), str(i * j))
        }
      } else {
        if i == j {
          // the top right corner 
          $times$
        } else {
          // on of them is zero, we are at top/left
          $#{i + j}$
        }
      }
      // this is an array, for loops merge them together
      // into one large array of cells
      (
        table.cell(
          fill: if i == j and j == 0 { orange } // top right corner
          else if i == j { yellow } // the diagonal
          else if i * j == 0 { blue.lighten(50%) }, // multipliers
          product,),
      )
    }
  }
}

#let n = 10
#table(
  columns: (0.6cm,) * (n + 1), rows: (0.6cm,) * (n + 1), align: center + horizon, inset: 3pt, ..yield_cells(n),
)

#table(
  columns: 2,
  fill: (x, y) => if y == 2 { highlight.fill },
  [A], [B],
  [C], [D],
  [E], [F],
  [G], [H],
)

#table(
  columns: 2,
  [A], [B],
  table.cell(fill: yellow)[C], table.cell(fill: yellow)[D],
  [E], [F],
  [G], [H],
)

#set page(height: 8em)
#(
table(
  columns: 5,
  [Aligner], [publication], [Indexing], [Pairwise alignment], [Max. read length  (bp)],
  [BWA], [2009], [BWT-FM], [Semi-Global], [125],
  [Bowtie], [2009], [BWT-FM], [HD], [76],
  [CloudBurst], [2009], [Hashing], [Landau-Vishkin], [36],
  [GNUMAP], [2009], [Hashing], [NW], [36]
  )
)

#set page(height: 8em)
// Without this, the table fails to split upon several pages
#show figure: set block(breakable: true)
#figure(
table(
  columns: 5,
  [Aligner], [publication], [Indexing], [Pairwise alignment], [Max. read length  (bp)],
  [BWA], [2009], [BWT-FM], [Semi-Global], [125],
  [Bowtie], [2009], [BWT-FM], [HD], [76],
  [CloudBurst], [2009], [Hashing], [Landau-Vishkin], [36],
  [GNUMAP], [2009], [Hashing], [NW], [36]
  )
)

#import "@preview/treet:0.1.1": *

#show list: tree-list
#set par(leading: 0.8em)
#show list: set text(font: "DejaVu Sans Mono", size: 0.8em)
- chapters/
  - chapter_1.typ
  - chapter_2.typ
- main.typ 👁 #text(gray)[← document entry point]
- template.typ

// template.typ

#let template = doc => {
    set page(header: "My super document")
    show "physics": "magic"
    doc
}

#let info-block = block.with(stroke: blue, fill: blue.lighten(70%))
#let author = "@sitandr"

// main.typ

#import "template.typ": *
// if you have a template
#show: template

= This is the document title

// some additional formatting

#show emph: set text(blue)

// but don't define functions or variables there!
// chapters will not see it

// Now the chapters themselves as some Typst content
#include("chapters/chapter_1.typ")
#include("chapters/chapter_1.typ")

// chapter_1.typ

#import "../template.typ": *

That's just content with _styling_ and blocks:

#infoblock[Some information].

// just any content you want to include in the document

#let author = "John Doe"

This is a book by #author. #author is a great guy.

#quote(block: true, attribution: author)[
  \<Some quote\>
]

#let block_text = block(stroke: red, inset: 1em)[Text]

#block_text

#figure(caption: "The block", block_text)

// This is a syntax that we have seen earlier
#let f = (name) => "Hello, " + name

#f("world!")

// The following syntaxes are equivalent
#let f = (name) => "Hello, " + name
#let f(name) = "Hello, " + name

#f("world!")

#let v = [Some text, _markup_ and other #strong[functions]]
#v

#let f(name) = [Hello, #name]
#f[World] // also don't forget we can use it to pass content!

#let f(name) = {
  // this is code mode

  // First part of our output
  "Hello, "

  // we check if name is empty, and if it is,
  // insert placeholder
  if name == "" {
      "anonym"
  } else {
      name
  }

  // finish sentence
  "!"
}

#f("")
#f("Joe")
#f("world")

#{
  let a = 3;
}
// can't use "a" there.

#[
  #show "true": "false"

  This is true.
]

This is true.

#let change_world() = {
  // some code there changing everything in the world
  str(4e7)
  // another code changing the world
}

#let g() = {
  "Hahaha, I will change the world now! "
  change_world()
  " So here is my long evil monologue..."
}

#g()

#let f() = {
  "Some long text"
  // Crazy numbers
  "2e7"
  return none
}

// Returns nothing
#f()

#let f(name: "anonym") = [Hello, #name!]

#f()
#f(name: "Joe")
#f(name: "world")

#let c = [It is _content_!]

// Check type of c
#(type(c) == content)

#c

// repr gives an "inner representation" of value
#repr(c)

#none
#repr(none)

#let s = "Some large string. There could be escape sentences: \n,
 line breaks, and even unicode codes: \u{1251}"
#s \
#type(s) \
`repr`: #repr(s)

#let s = "another small string"
#s.replace("a", sym.alpha) \
#s.split(" ") // split by space

#str(5) // string, can be worked with as string

#let b = false
#b \
#repr(b) \
#(true and not true or true) = #((true and (not true)) or true) \
#if (4 > 3) {
  "4 is more than 3"
}

#let n = 5
#n \
#(n += 1) \
#n \
#calc.pow(2, n) \
#type(n) \
#repr(n)

#(1 + 2) \
#(2 - 5) \
#(3 + 4 < 8)

#0xff \
#0o10 \
#0b1001

#int(false) \
#int(true) \
#int(2.7) \
#(int("27") + int("4"))

#let n = 5.0

// You can mix floats and integers, 
// they will be implicitly converted
#(n += 1) \
#calc.pow(2, n) \
#(0.2 + 0.1) \
#type(n) 

#3.14 \
#1e4 \
#(10 / 4)

#float(40%) \
#float("2.7") \
#float("1e5")

#let values = (1, 7, 4, -3, 2)

// take value at index 0
#values.at(0) \
// set value at 0 to 3
#(values.at(0) = 3)
// negative index => start from the back
#values.at(-1) \
// add index of something that is even
#values.find(calc.even)

#let values = (1, 7, 4, -3, 2)

// leave only what is odd
#values.filter(calc.odd) \
// create new list of absolute values of list values
#values.map(calc.abs) \
// reverse
#values.rev() \
// convert array of arrays to flat array
#(1, (2, 3)).flatten() \
// join array of string to string
#(("A", "B", "C")
 .join(", ", last: " and "))

// sum of lists:
#((1, 2, 3) + (4, 5, 6))

// list product:
#((1, 2, 3) * 4)

#() \ // this is an empty list
#(1,) \  // this is a list with one element
BAD: #(1) // this is just an element, not a list!

#let dict = (
  name: "Typst",
  born: 2019,
)

#dict.name \
#(dict.launch = 20)
#dict.len() \
#dict.keys() \
#dict.values() \
#dict.at("born") \
#dict.insert("city", "Berlin ")
#("name" in dict)

This is an empty list: #() \
This is an empty dict: #(:)

#if 1 < 2 [
  This is shown
] else [
  This is not.
]

#let a = 3

#if a < 4 {
  a = 5
}

#a

#let a = 5

#if a < 4 {
  a = 5
} else if a < 6 {
  a = -3
}

#a

#let a = 5

#if (a > 1 and a <= 4) or a == 5 [
    `a` matches the condition
]

#let a = 3

#while a < 100 {
    a *= 2
    str(a)
    " "
}

#for c in "ABC" [
  #c is a letter.
]

#let s = 0

#for i in range(3, 6) {
    s += i
    [Number #i is added to sum. Now sum is #s.]
}

#let s = 0

#for i in (3, 4, 5) {
    s += i
    [Number #i is added to sum. Now sum is #s.]
}

#let people = (Alice: 3, Bob: 5)

#for (name, value) in people [
    #name has #value apples.
]

#for letter in "abc nope" {
  if letter == " " {
    // stop when there is space
    break
  }

  letter
}

#for letter in "abc nope" {
  if letter == " " {
    // skip the space
    continue
  }

  letter
}

#let func(a, b, c, d, e) = [#a #b #c #d #e]
#func(..(([hi],) * 5))

#let a = ("hi", "b", "c")

#table(columns: 3,
  [test], [x], [hello],
  ..a
)

#let text-params = (fill: blue, size: 0.8em)

Some #text(..text-params)[text].

#let f(..args) = [
  #args.pos()\
  #args.named()
]

#f(1, "a", width: 50%, block: false)

#let format(title, ..authors) = {
  let by = authors
    .pos()
    .join(", ", last: " and ")

  [*#title* \ _Written by #by;_]
}

#format("ArtosFlow", "Jane", "Joe")

#let a = 7
#let b = 7.0
#(a == b)
#(type(a) == type(b))

#let a = (x: 1, y: 2)
#let b = (y: 2, x: 1)
#(a == b)
#(a.pairs() == b.pairs())

#let dict = (a: 1, b: 2)

#("a" in dict)
// gives the same as
#(dict.keys().contains("a"))

#("a" in ("b", "c", "a"))
#(("b", "c", "a").contains("a"))

#let x = 0
#let compute(expr) = {
  // eval evaluates string as Typst code
  // to calculate new x value
  x = eval(
    expr.replace("x", str(x))
  )
  [New value is #x.]
}

#compute("10") \
#compute("x + 3") \
#compute("x * 2") \
#compute("x - 5")

#let s = state("x", 0)
#let compute(expr) = [
  // updates x current state with this function
  #s.update(x =>
    eval(expr.replace("x", str(x)))
  )
  // and displays it
  New value is #context s.get().
]

#compute("10") \
#compute("x + 3") \
#compute("x * 2") \
#compute("x - 5")

The computations will be made _in order_ they are _located_ in the document. So if you create computations first, but put them in the document later... See yourself:

#let more = [
  #compute("x * 2") \
  #compute("x - 5")
]

#compute("10") \
#compute("x + 3") \
#more

#let x = state("state-id")
#let y = state("state-id", 2)

#x, #y

State is #context x.get() \ // the same as
#context [State is #y.get()] \ // the same as
#context {"State is" + str(y.get())}

#let x = state("x", 0)
#context x.get() \
#let _ = x.update(3)
// nothing happens, we don't put `update` into the document flow
#context x.get()

#repr(x.update(3)) // this is how that content looks \

#context x.update(3)
#context x.get() // Finally!

#let x = state("x", 0)

#context {
  x.update(3)
  str(x.get())
}

#let f(x) = {
  // return new state…
  // …but their id-s are the same!
  // so it will always be the same state!
  let y = state("x", 0)
  y.update(y => y + x)
  context y.get()
}

#let a = f(2)
#let b = f(3)

#a, #b \
#raw(repr(a) + "\n" + repr(b))

// locations in code are different!
#let x = state("state-id")
#let y = state("state-id", 2)

#x, #y

#let x = state("state-id")
#let y = state("state-id", 2)

#context [#x.get(); #y.get()]

#x.update(3)

#context [#x.get(); #y.get()]

#set heading(numbering: "1.")

= Background
#counter(heading).update(3)
#counter(heading).update(n => n * 2)

== Analysis
Current heading number: #counter(heading).display().

#let mine = counter("mycounter")
#mine.display()

#mine.step()
#mine.display()

#mine.update(c => c * 3)
#mine.display()

#set heading(numbering: "1.")

= Introduction
Some text here.

= Background
The current value is:
#counter(heading).display()

Or in roman numerals:
#counter(heading).display("I")

#set heading(numbering: "1.")

= Introduction
Some text here.

#counter(heading).display(both: true) \
#counter(heading).display("1 of 1", both: true) \
#counter(heading).display(
  (num, max) => [#num of #max],
   both: true
)

= Background
The current value is: #counter(heading).display()

#set heading(numbering: "1.")

= Introduction
#counter(heading).step()

= Analysis
Let's skip 3.1.
#counter(heading).step(level: 2)

== Analysis
At #counter(heading).display().

#let c = counter("theorem")
#let theorem(it) = block[
  #c.step()
  *Theorem #c.display():*
  #it
]

#theorem[$1 = 1$]
#theorem[$2 < 3$]

#let content = [Hello!]
#content
#set text(14pt)
#content

#let thing(body) = style(styles => {
  let size = measure(body, styles)
  [Width of "#body" is #size.width]
})

#thing[Hey] \
#thing[Welcome]

#layout(size => {
  let half = 50% * size.width
  [Half a page is #half wide.]
})

#let text = lorem(30)
#layout(size => style(styles => [
  #let (height,) = measure(
    block(width: size.width, text),
    styles,
  )
  This text is #height high with
  the current page width: \
  #text
]))

#let s = state("x", 0)
#let compute(expr) = [
  #s.update(x =>
    eval(expr.replace("x", str(x)))
  )
  New value is #s.display().
]

Value at `<here>` is
#context s.at(
  query(<here>)
    .first()
    .location()
)

#compute("10") \
#compute("x + 3") \
*Here.* <here> \
#compute("x * 2") \
#compute("x - 5")

#set page(header: context {
  let elems = query(
    selector(heading).before(here()),
    here(),
  )
  let academy = smallcaps[
    Typst Academy
  ]
  if elems == () {
    align(right, academy)
  } else {
    let body = elems.last().body
    academy + h(1fr) + emph(body)
  }
})

= Introduction
#lorem(23)

= Background
#lorem(30)

= Analysis
#lorem(15)

// Put metadata somewhere.
#metadata("This is a note") <note>

// And find it from anywhere else.
#context {
  query(<note>).first().value
}

// This is inline math
Let $a$, $b$, and $c$ be the side
lengths of right-angled triangle.
Then, we know that:

// This is display math
$ a^2 + b^2 = c^2 $

Prove by induction:

// You can use new lines as spacing too!
$
sum_(k=1)^n k = (n(n+1)) / 2
$

#show math.equation: set text(red)

$
integral_0^oo (f(t) + g(t))/2
$

#math.integral, #math.underbrace([a + b], [c])

$
a = b\
a = c
$

$
a  / b \
a \/ b
$

#lorem(17) $display(1)/display(1+x^n)$ #lorem(20)

#lorem(17) #box($display(1)/display(1+x^n)$, inset: 0.2em) #lorem(20)

$
forall v, w in V, alpha in KK: alpha dot (v + w) = alpha v + alpha w
$

$
∀ v, w ∈ V, α ∈ 𝕂: α ⋅ (v + w) = α v + α w
$

$
// cont — contour
integral, integral.cont, integral.double, integral.square, sum.integral\

// lt — less than, gt — greater than
lt, lt.circle, lt.eq, lt.not, lt.eq.not, lt.tri, lt.tri.eq, lt.tri.eq.not, gt, lt.gt.eq, lt.gt.not
$

$
gt.nequiv, gt.napprox, gt.ntilde, gt.tilde.not
$

$
alpha, Alpha, beta, Beta, beta.alt, gamma, pi, Pi,\
pi.alt, phi, phi.alt, Phi, omicron, kappa, kappa.alt, Psi,\
theta, theta.alt, xi, zeta, rho, rho.alt, kai, Kai,
$

$bb(A), AA, bb(1)$

// nothing in default math font is something bad
$nothing, nothing.rev, diameter$

#show math.equation: set text(font: "Fira Math")

// Fira math is more consistent
$nothing, nothing.rev, diameter$

#show math.equation: set text(features: ("cv01",))

$nothing, nothing.rev, diameter$

#show math.nothing: math.diameter

$nothing, nothing.rev, diameter$

$ (a^2 + b^2)/2 $

$
{[((a + b)/2) + 1]_0}
$

$
lr([a/2, b)) \
lr([a/2, b), size: #150%)
$

$
abs(a + b), norm(a + b), floor(a + b), ceil(a + b), round(a + b)
$

#show math.equation: set align(right)

$
(a + b)/2
$

#align(left, block($ x = 5 $))

$ (3x + y) / 7 &= 9 && "given" \
  3x + y &= 63 & "multiply by 7" \
  3x &= 63 - y && "subtract y" \
  x &= 21 - y/3 & "divide by 3" $

$
integral_a^b\
limits(integral)_a^b
$

#show math.integral: math.limits

$
integral_a^b
$

This is inline equation: $integral_a^b$

#show math.integral: math.limits.with(inline: false)

$
integral_a^b
$

This is inline equation: $integral_a^b$.

$
sum_a^b, scripts(sum)_a^b
$

$a =_"By lemme 1" b, a scripts(=)_+ b$

$
lim x_n, "lim" x_n, "lim"x_n
$

$
arccos, arcsin, arctan, arg, cos, cosh, cot, coth, csc,\
csch, ctg, deg, det, dim, exp, gcd, hom, id, im, inf, ker,\
lg, lim, liminf, limsup, ln, log, max, min, mod, Pr, sec,\
sech, sin, sinc, sinh, sup, tan, tanh, tg "and" tr
$

#let arcsinh = math.op("arcsinh")

$
arcsinh x
$

$
op("liminf")_a, op("liminf", limits: #true)_a
$

$
limits(op("liminf"))_a
$

#let liminf = math.op(math.underline(math.lim), limits: true)
#let limsup = math.op(math.overline(math.lim), limits: true)
#let integrate = math.op($integral dif x$)

$
liminf_(x->oo)\
limsup_(x->oo)\
integrate x^2
$

Inline: $a/(b + 1/c), sum_(n=0)^3 x_n$

$
a/(b + 1/c), sum_(n=0)^3 x_n
$

$
"display:" 1/("inline:" a + 1/("script:" b + 1/("sscript:" c + 1/("sscript:" d + 1/("sscript:" e + 1/f)))))
$

Inine: $sum_0^oo e^x^a$\
Inline with limits: $limits(sum)_0^oo e^x^a$\
Inline, but like true display: $display(sum_0^oo e^x^a)$

$
vec(a, b, c) + vec(1, 2, 3) = vec(a + 1, b + 2, c + 3)
$