Sorting in Go using the built in interface methods on a user defined type

sorting.go

package main

import (
	"fmt"
	"sort"
	"time"
)

type Event struct {
	Description string
	Date        time.Time
	Kind        string
}

type ByDate []Event

func (b ByDate) Len() int           { return len(b) }
func (b ByDate) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
func (b ByDate) Less(i, j int) bool { return b[i].Date.Hour() < b[j].Date.Hour() }

type ByDescription []Event

func (b ByDescription) Len() int           { return len(b) }
func (b ByDescription) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
func (b ByDescription) Less(i, j int) bool { return b[i].Description < b[j].Description }

type ByKind []Event

func (b ByKind) Len() int           { return len(b) }
func (b ByKind) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }
func (b ByKind) Less(i, j int) bool { return b[i].Kind < b[j].Kind }

func main() {

	events := make([]Event, 0, 3)
	events = append(events, Event{"DELIVERED", time.Now().Add(3 * time.Hour), "PROCESSED"})
	events = append(events, Event{"SCANNED AT DEPOT", time.Now().Add(1 * time.Hour), "SCAN"})
	events = append(events, Event{"ON VAN", time.Now().Add(2 * time.Hour), "SCAN"})

	sort.Sort(ByKind(events))

	for i, _ := range events {
		fmt.Printf("%20s - %40v\n", events[i].Description, events[i].Date)
	}
}