For loops

Run uses for as its only loop construct. It covers all common looping patterns.

Infinite loop

A bare for loops forever. Use break to exit.

for {
    // runs forever
    break
}

Conditional loop

A for with a condition works like while in other languages.

package main

use "fmt"

pub fun main() {
    x := 0
    for x < 10 {
        fmt.println(x)
        x = x + 1
    }
}

Range loop

Use in with a range expression to iterate over a sequence of numbers.

package main

use "fmt"

pub fun main() {
    for i in 0..5 {
        fmt.println(i) // prints 0, 1, 2, 3, 4
    }
}

Iterator loop

Use in to iterate over any iterable value like slices or strings.

package main

use "fmt"

pub fun main() {
    names := []string{"Alice", "Bob", "Charlie"}
    for name in names {
        fmt.println(name)
    }
}