func AtHead ¶

func AtHead[A any]() L.Lens[[]A, O.Option[A]]

AtHead focusses on the head of an array. The setter works as follows - if the new value is none, the result will be an empty array - if the new value is some and the array is empty, it creates a new array with one element - if the new value is some and the array is not empty, it replaces the head