Is there a legitimate reason for `never`

Request Feedback
3

Another use case for Never is with phantom types.

type Point coordinateSystem = Point Float Float

type WorldCoordinate = WorldCoordinate Never

type ScreenCoordinate = ScreenCoordinate Never

playerStartPos : Point WorldCoordinate
playerStartPos = Point 2 3

healthBarPos : Point ScreenCoordinate
healthBarPos = Point 200 10

Here I’ve defined Point that uses a type parameter to make sure I don’t mix up different coordinate systems. I don’t actually want to create an instance of these coordinate systems though, they are just being used as phantom types. So to prevent accidentally creating them I add Never to their constructor.

14 Likes