You live and breathe http. Most of the things you do with a computer involve it. How many tiny little http-related utils have you already created? Is it time to stop? By no means, we all do it. I'd just like to encourage you to write the next one in Go. It's a fun little language, which feels like a cross-breed between C (pointers!) and ruby (concise, powerful syntax). But how much? Why, yet another language, but my perl/python/.. does all the things? Well, it does. But go has a few things that make it super sweet, is web-scale and real fun to use!

1. golang
the one language you have to try in 2014

2. golang
the one language you have to try in 2014

3. Andrzej Grzesik
!
!
!
@ags313
andrzej@grzesik.it
andrzejgrzesik.info

4. about:me

5. dev going deeper

6. disclaimers

7. my opinions are my own

8. I hate computers

9. questions?
shoot!

10. golang

11. gopher

12. free and open source

13. BSD licensed

14. comes from G

15. FAST
and I mean FAST

16. tl;dr;
C++ and ruby had a wild time

17. play with it tonight

18. so, why do I like go?

19. no runtime dependencies!

20. more pleasant than C

21. go toolchain

22. go command

23. most important thing

24. there is only one formatting

25. package main!
!
import "fmt"!
!
func main() {!
!fmt.Println("Hello world")!
}!

26. types

27. types
• uint8, uint16, uint32, uint64
• int8, int16, int32, int64
• float32, float64
• complex64, complex128
• byte alias for uint8
• rune alias for int32
• string

28. func program() {!
var text!
text = “zomg"!
more := "zomg"!
!
fmt.Println(len(text));!
}!

29. maps

30. func main() {!
attendees := map[string]bool{!
"Phil": true,!
"Marcin": true,!
}!
!
fmt.Println(attendees["Phil"]) // true!
fmt.Println(attendees["ags"]) // false!
partygoers["ags"] = true!
fmt.Println(attendees["ags"]) // true!
}!

31. structs

32. type Rectangle struct {!
a, b int32!
}!
!
func main() {!
var rect Rectangle!
rect = Rectangle{5, 10}!
rect = Rectangle{a: 10, b: 5}!
!
HasArea(s).Area()!
}

33. type Square struct {!
side int32!
}!
!
func (sq Square) Area() int32 {!
return sq.side * sq.side!
}!
!
func main() {!
s := Square{16}!
area := s.Area()!
}

34. interfaces

35. type Square struct {!
side int32!
}!
!
func (sq Square) Area() int32 {!
return sq.side * sq.side!
}!
!
type HasArea interface {!
Area() int32!
}!
!
func main() {!
s := Square{16}!
HasArea(s).Area()!
}

36. goroutines
lightweight threads

37. func f(i int) {!
amt := rand.Intn(1000)!
time.Sleep(time.Duration(amt) * time.Millisecond)!
fmt.Println(i)!
}!
!
func main() {!
for i := 0; i < 3; i++ {!
go f(i)!
}!
var input string!
fmt.Scanln(&input)!
}

38. how many will run?
runtime.GOMAXPROCS(4)

39. channels

40. channels
• communicate between funcs
• typed
• thread-safe

41. channels
channel := make(chan int)!

42. unbuffered channels
• sync
• will wait when empty

43. buffered channels
channel := make(chan int, size)!

44. buffered channels
• async
• return 0 element when empty
• will only wait when full

45. basics
channel := make(chan int)!
c <- a!
!
<- c!
!
a = <- c!
!
a, ok = <- c!

46. func program() {!
channel := make(chan int) !
}!
!
func from(connection chan int) {!
connection <- rand.Intn(255)!
}!
!
func to(connection chan int) {!
i := <- connection!
fmt.Println(“much received", i)!
}!

47. but that’s not cool yet

48. coordinate routines

49. func program() {!
channel := make(chan int) !
!
go func() {!
close(channel)!
// or!
channel <- anything!
}()!
!
<- channel!
}!

50. func program() {!
latch := make(chan int) !
!
go worker()!
close(latch)!
}!
!
func worker() {!
<- latch !
}!

51. generators

52. id := make(chan int64)!
go func() {!
var counter int64 = 0!
for {!
id <- counter!
counter += 1!
} !
}()

53. multiple channels at once!

54. func program() {!
select {!
case a := <- channel!
!
case b, mkay := other!
!
case output <- z!
!
default:!
}!
}!

55. ranges

56. func fillIn(channel chan int) {!
channel <- 1!
channel <- 2!
channel <- 4!
close(channel)!
}!
!
func main() {!
channel := make(chan int)!
go fillIn(channel)!
!
for s := range channel {!
fmt.Printf("%d n", s)!
}!
}

57. packages

58. [18:48][agrzesik@melmac:~/vcs/talks/go/hello]!
$ find .!
.!
./bin!
./bin/main!
./pkg!
./pkg/darwin_amd64!
./pkg/darwin_amd64/hello.a!
./src!
./src/hello!
./src/hello/hello.go!
./src/main!
./src/main/.main.go.swp!
./src/main/main.go!

59. import (!
"code.google.com/p/go.net/websocket"!
"fmt"!
"net/http"!
)!

60. go get

61. net

62. echo server

63. const listenAddr = "localhost:4000"!
!
func main() {!
l, err := net.Listen("tcp", listenAddr)!
if err != nil {!
log.Fatal(err)!
}!
for {!
c, err := l.Accept()!
if err != nil {!
log.Fatal(err)!
}!
io.Copy(c, c)!
}!
}

64. concurrent echo server

65. const listenAddr = "localhost:4000"!
!
func main() {!
l, err := net.Listen("tcp", listenAddr)!
if err != nil {!
log.Fatal(err)!
}!
for {!
c, err := l.Accept()!
if err != nil {!
log.Fatal(err)!
}!
go io.Copy(c, c)!
}!
}

66. const listenAddr = "localhost:4000"!
!
func main() {!
l, err := net.Listen("tcp", listenAddr)!
if err != nil {!
log.Fatal(err)!
}!
for {!
c, err := l.Accept()!
if err != nil {!
log.Fatal(err)!
}!
io.Copy(c, c)!
}!
}

67. websockets?

68. func main() {!
http.Handle("/", websocket.Handler(handler))!
http.ListenAndServe("localhost:1984", nil)!
}!
!
func handler(c *websocket.Conn) {!
var s string!
fmt.Fscan(c, &s)!
fmt.Println("Received:", s)!
fmt.Fprint(c, “hey!”)!
}!

69. so, what looks bad?

70. type AssetMetas struct {!
! Metas []AssetMeta `json:"assetMetas"`!
}!
!
type AssetMeta struct {!
! ResourceName string `json:"resource_name"`!
! Md5 string `json:"md5"`!
! Urls []string `json:"urls"`!
}!

71. so, go code!