Golang : How to calculate the distance between two coordinates using Haversine formula

I need to develop a service that calculate the distances of my current location to several points nearby. Each of the locations are represented by coordinates and my service will pick the 3 nearest points and select one of them. So, how to calculate the distances of my current location to each and every points?

Below is a simple example using the Haversine formula to calculate the distance between 2 coordinates.

Here you go!

 package main

 import (
  "fmt"
  "math"
 )

 type Coordinates struct {
  Latitude  float64
  Longitude float64
 }

 const radius = 6371 // Earth's mean radius in kilometers

 func degrees2radians(degrees float64) float64 {
  return degrees * math.Pi / 180
 }

 func (origin Coordinates) Distance(destination Coordinates) float64 {
  degreesLat := degrees2radians(destination.Latitude - origin.Latitude)
  degreesLong := degrees2radians(destination.Longitude - origin.Longitude)
  a := (math.Sin(degreesLat/2)*math.Sin(degreesLat/2) +
 math.Cos(degrees2radians(origin.Latitude))*
 math.Cos(degrees2radians(destination.Latitude))*math.Sin(degreesLong/2)*
 math.Sin(degreesLong/2))
  c := 2 * math.Atan2(math.Sqrt(a), math.Sqrt(1-a))
  d := radius * c

  return d
 }

 func main() {
  pointA := Coordinates{2.990353, 101.533913}
  pointB := Coordinates{2.960148, 101.577888}

  fmt.Println("Point A : ", pointA)
  fmt.Println("Point B : ", pointB)

  distance := pointA.Distance(pointB)
  fmt.Printf("The distance from point A to point B is %.2f kilometers.\n", distance)

 }

Sample output:

Point A : {2.990353 101.533913}

Point B : {2.960148 101.577888}

The distance from point A to point B is 5.93 kilometers.

References :

https://stackoverflow.com/questions/27928/calculate-distance-between-two-latitude-longitude-points-haversine-formula

https://en.wikipedia.org/wiki/Haversine_formula

https://en.wikipedia.org/wiki/Earth_radius