Using GPIO pins with GoLang

gpio.go

package main

import "os"
import "io/ioutil"
import "time"

type GPIO struct{}

func (r GPIO) Pin(name string) GPIO_Pin {
        pin := GPIO_Pin{name}
        filename := pin.Filename()
        if _, err := os.Stat(filename); os.IsNotExist(err) {
                // export gpio pin
                ioutil.WriteFile("/sys/class/gpio/export", []byte(pin.Name), 0666)
        }
        return pin
}

type GPIO_Pin struct {
        Name string
}

func (r GPIO_Pin) Filename() string {
        return "/sys/class/gpio/gpio" + r.Name
}
func (r GPIO_Pin) write(where, what string) GPIO_Pin {
        filename := r.Filename() + "/" + where
        ioutil.WriteFile(filename, []byte(what), 0666)
        return r
}
func (r GPIO_Pin) Output() GPIO_Pin {
        return r.write("direction", "out")
}
func (r GPIO_Pin) Input() GPIO_Pin {
        return r.write("direction", "in")
}
func (r GPIO_Pin) High() GPIO_Pin {
        return r.write("value", "1")
}
func (r GPIO_Pin) Low() GPIO_Pin {
        return r.write("value", "0")
}

func main() {
        pins1 := []string{"26", "19", "13", "6"}
        pins2 := []string{"24", "23", "18", "25", "12", "16", "21", "20"}

        i := 0
        gpio := GPIO{}
        for i < 1600 {
                i1 := (i) % len(pins1)
                gpio.Pin(pins1[i1]).Output().Low()

                i2 := (i) % len(pins2)
                gpio.Pin(pins2[i2]).Output().Low()

                i3 := (i + 4) % len(pins2)
                gpio.Pin(pins2[i3]).Output().Low()

                time.Sleep(200 * time.Millisecond)

                gpio.Pin(pins1[i1]).High()
                gpio.Pin(pins2[i2]).High()
                gpio.Pin(pins2[i3]).High()
                i++
        }
}