Iter

The @std/iter module provides low-level iterator helper structs.

It exposes:

Name	Kind	Description
Progress	struct	Represents one iterator step.
End	value	A progress value where end is true.
Iterator	struct	Wraps a function that returns Progress.

iter.Progress

Progress represents one iterator step.

Field	Type	Description
key	any	Step key or index.
value	any	Step value.
end	bool	Whether iteration has finished.

import iter from "@std/iter"

let step = iter.Progress(0, "first")

println(step.key)
println(step.value)
println(step.end)

iter.End

End is a ready-made Progress value with end set to true.

import iter from "@std/iter"

let done = iter.End

println(done.end)

iter.Iterator

Iterator wraps a function that returns a Progress.

The wrapped function type is:

let nextStep: fn() -> iter.Progress

Example:

import iter from "@std/iter"

let index = 0
let values = ["a", "b", "c"]

fn nextValue() iter.Progress {
    if index >= len(values) {
        return iter.End
    }

    let current = iter.Progress(index, values[index])
    index = index + 1

    return current
}

let iterator = iter.Iterator(nextValue)

let step = iterator.next()

while !step.end {
    println(step.key, step.value)

    step = iterator.next()
}

iterator.next

Returns the next Progress.

Returns: Progress

let step = iterator.next()