Conditions & loops

Conditions

See official documentation.

In Typst, you can use if-else statements. This is especially useful inside function bodies to vary behavior depending on arguments types or many other things.

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

Of course, else is unnecessary:

#let a = 3

#if a < 4 {
  a = 5
}

#a

You can also use else if statement (known as elif in Python):

#let a = 5

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

#a

Booleans

if, else if, else accept only boolean values as a switch. You can combine booleans as described in types section:

#let a = 5

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

Loops

See official documentation.

There are two kinds of loops: while and for. While repeats body while the condition is met:

#let a = 3

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

for iterates over all elements of sequence. The sequence may be an array, string or dictionary (for iterates over its key-value pairs).

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

To iterate to all numbers from a to b, use range(a, b+1):

#let s = 0

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

Because range is end-exclusive this is equal to

#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.
]

Break and continue

Inside loops can be used break and continue commands. break breaks loop, jumping outside. continue jumps to next loop iteration.

See the difference on these examples:

#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
}