Calculations between points on the earth.
distanceBetween : { a | latitude : Basics.Float, longitude : Basics.Float } -> { b | latitude : Basics.Float, longitude : Basics.Float } -> Basics.Float
Calculate the distance in kilometers between two points.
Note that this assumes the earth is spherical, which is not true, but may be true enough for your purposes.
bearingTo : { a | latitude : Basics.Float, longitude : Basics.Float } -> { b | latitude : Basics.Float, longitude : Basics.Float } -> Basics.Float
Calculate the heading you'd need to travel on to get from point a to point b.