Traversals

Travarsals are optics that can have more than one focus. These foci can be filtered by composing with an optional, or further multiplied by composing with another traversal.

const focus = flow(
	eq<number[]>(),
	elems(),
	when((x) => x % 2 === 0),
)
put(focus, 9)([0, 1, 2, 3]) // [9, 1, 9, 3]