# Playing with Google Go

I finally found 20 minutes to have my first trial of the recent addition to Googleâ€™s arsenal; Google Go. Having been working a lot with distances lately I decided to implement Haversine formula in Google Go, my next stop will hopefully be to tie this in with Google Maps API and trying to do something clever.

Try the code in the go playground

```
package main
import "fmt"
import "math"
const kmtomiles = float64(0.621371192)
const earthRadius = float64(6371)
func main() {
var locationName [2]string
var location [2][2]float64
// York - lat,lon
locationName[0] = "York"
location[0][0] = 1.0803
location[0][1] = 53.9583
// Bristol - lat,lon
locationName[1] = "Bristol"
location[1][0] = 2.5833
location[1][1] = 51.4500
// Use haversine to get the resulting diatance between the two values
var distance = Haversine(location[0][0], location[0][1], location[1][0], location[1][1])
// We wish to use miles so will alter the resulting distance
var distancemiles = distance * kmtomiles
fmt.Printf("The distance between %s and %s is %.02f miles as the crow flies", locationName[0], locationName[1], distancemiles)
}
/*
* The haversine formula will calculate the spherical distance as the crow flies
* between lat and lon for two given points in km
*/
func Haversine(lonFrom float64, latFrom float64, lonTo float64, latTo float64) (distance float64) {
var deltaLat = (latTo - latFrom) * (math.Pi / 180)
var deltaLon = (lonTo - lonFrom) * (math.Pi / 180)
var a = math.Sin(deltaLat / 2) * math.Sin(deltaLat / 2) +
math.Cos(latFrom * (math.Pi / 180)) * math.Cos(latTo * (math.Pi / 180)) *
math.Sin(deltaLon / 2) * math.Sin(deltaLon / 2)
var c = 2 * math.Atan2(math.Sqrt(a),math.Sqrt(1-a))
distance = earthRadius * c
return
}
```

A site I found really useful, and well worth checking out is go by example.