Don t Go Java! Edition 2019

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Ralf Simmons
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1 Don t Go, Java!

2 Don t Go Java!

3 Don t Go Java! Edition 2019

4 Disclaimer

5 Disclaimer I actually like Go!

6 Guess The Movie

7 Guess The Movie

8 Guess The Movie

9 Guess The Movie

10 Who s That Dude? Chris Engelbert Senior Developer Instana Java-Passionate (10+ years) Go (2 years) Performance Garbage Collection Benchmark Fairytales

11 Who s That

12 Who s That Dude? Adores TypeScript Prefers Kotlin Codes

13 Who s That Dude? Kinda likes Go Adores TypeScript Prefers Kotlin Codes

14 Who s That Dude? Kinda likes Go Adores TypeScript Forced to use JS Prefers Kotlin Totally hates Python Codes

15 Who s That Dude? Kinda likes Go Adores TypeScript Forced to use JS Prefers Kotlin Totally hates Python Codes Java LOVES BEER! (Dah,

16 What is?

17 What Is Go? s t r a P d o o G e h T : Go d e t a nion i p o s t I. 1

18 What Is Go? General Purpose Language Inception: 2009 Version 1.0: 2012 Current Release:

19 What Is Go?

20 What Is Go? Type Inference package main func main() { value := "my string"

21 What Is Go? Type Inference Package Declaration package main func main() { value := "my string"

22 What Is Go? Type Inference Package Declaration package main Main (Entry) Function func main() { value := "my string"

23 What Is Go? Type Inference Package Declaration package main Main (Entry) Function Variable Declaration func main() { value := "my string"

24 What Is Go? Type Inference Package Declaration package main Main (Entry) Function Variable Declaration func main() { value := "my string" Variable

25 What Is Go? Type Inference Package Declaration package main Main (Entry) Function Variable Declaration func main() { value := "my string" Variable Create and Infer Type

26 What Is Go? Type Inference Package Declaration package main Main (Entry) Function Variable Declaration func main() { value := "my string" Variable Some String Create and Infer Type

27 What Is Go? Type Inference package main func main() { value := "my string"

28 What Is Go? Type Inference package main func main() { value := "my string" Compile Error

29 What Is Go? Type Inference package main func main() { value := "my string Compile Error

30 What Is Go? Extensive Stdlib package main import "io/ioutil" func main() {

31 What Is Go? Extensive Stdlib package main Import Declaration import "io/ioutil" func main() {

32 What Is Go? Extensive Stdlib Archive (tar, zip, ) Sorting Byte Manipulation Math HTML Templates (Buffered) IO Time Debugging Reflection OS (Exec, File, ) Database (SQL) Encoding (base64, hex, csv, json, xml, ) Compression (bzip2, flate, gzip, ) Crypto (aes, dsa, rsa, sha, tls, ) Logging Net (TCP, UDP, Unix Socket, )

33 What Is Go? Extensive Stdlib package main import "io/ioutil" func main() {

34 What Is Go? Extensive Stdlib package main import "io/ioutil" func main() { Compile Error

35 What Is Go? Extensive Stdlib package main import "io/ioutil" func main() { Compile Error

36 What Is Go? Multi-Value Return func main() { x, y := findcoordinates("conference") func findcoordinates(place string) (x, y int) { return 0, 0

37 What Is Go? Multi-Value Return func main() { x, y := findcoordinates("conference") func findcoordinates(place string) (x, y int) { return 0, 0 Defines Two Return Values (both type int)

38 What Is Go? Automatic Resource Management package main import "os" func main() { file, _ := os.open("/tmp/foo") defer file.close()

39 What Is Go? Automatic Resource Management package main import "os" func main() { ignore return value file, _ := os.open("/tmp/foo") defer file.close()

40 What Is Go? Automatic Resource Management package main import "os" func main() { ignore return value file, _ := os.open("/tmp/foo") defer file.close() file.close() should be called on Method return

41 What else is? Unfortunately!

42 What Is Go too? - Unfortunately Error Handling func main() { file, err := os.open("/tmp/foo") if err!= nil { log.fatal(err) defer file.close()

43 What Is Go too? - Unfortunately Error Handling func foo() error { file, err := os.open("/tmp/foo") if err!= nil { return err defer file.close() return nil

44 What Is Go too? - Unfortunately Public Vs. (Package) Private func Foo() { func foo() {

45 What Is Go too? - Unfortunately Public Vs. (Package) Private public func Foo() { func foo() { private

46 What Is Go too? - Unfortunately Public Vs. (Package) Private? func 日本語 () {

47 What Is Go too? - Unfortunately Public Vs. (Package) Private private func 日本語 () {

48 What Is Go too? - Unfortunately Syntax func (f *foo) method(p1 *string) (foo, error) { if p1 == nil { return "", errors.new("nil pointer") return "foo", nil

49 What Is Go too? - Unfortunately Syntax Bind Method to Type Pointer-To-Foo func (f *foo) method(p1 *string) (foo, error) { if p1 == nil { return "", errors.new("nil pointer") return "foo", nil

50 What Is Go too? - Unfortunately Syntax func (f *foo) method(p1 *string) (foo, error) { if p1 == nil { return "", errors.new("nil pointer") return "foo", nil

51 What Is Go too? - Unfortunately Syntax func (f *foo(*string)) method(p1 *string) (foo, error) { if p1 == nil { return "", errors.new("nil pointer") return "foo", nil

52 What Is Go too? - Unfortunately

53 5 Things You Can Hate About Go But You Don t Have To

54 You re Crazy, But Don t You Worry!

55 You re Crazy, But Don t You Worry! func foo(var1 string) { { var1 := "bar" fmt.println(var1) break func main() { foo("foo")

56 You re Crazy, But Don t You Worry! func foo(var1 string) { { fmt := "bar" fmt.println(var1) break func main() { foo("foo")

57 You re Crazy, But Don t You Worry! type task struct { func main() { task := &task{

58 You re Crazy, But Don t You Worry! type task struct { func main() { instantiation task := &task{

59 You re Crazy, But Don t You Worry! type task struct { func main() { task := &task{ task = &task{

60 Clone Or Not Clone, That Is The Question!

61 Clone Or Not Clone, That Is The Question! type handle int func types(val interface{) { switch v := val.(type) { case int: fmt.println(fmt.sprintf("i am an int: %d", v)) switch v := val.(type) { case handle: fmt.println(fmt.sprintf("i am an handle: %d", v))

62 Clone Or Not Clone, That Is The Question! type handle int func types(val interface{) { switch v := val.(type) { reflective type case int: fmt.println(fmt.sprintf("i am an int: %d", v)) switch v := val.(type) { case handle: fmt.println(fmt.sprintf("i am an handle: %d", v))

63 Clone Or Not Clone, That Is The Question! func main() { var var1 int = 1 var var2 handle = 2 type handle int types(var1) types(var2) func types(val interface{) { switch v := val.(type) { case int: fmt.println(fmt.sprintf("i am an int: %d", v)) switch v := val.(type) { case handle: fmt.println(fmt.sprintf("i am an handle: %d", v))

64 Clone Or Not Clone, That Is The Question! func main() { var var1 int = 1 var var2 handle = 2 type handle = int types(var1) types(var2) func types(val interface{) { switch v := val.(type) { case int: fmt.println(fmt.sprintf("i am an int: %d", v)) switch v := val.(type) { case handle: fmt.println(fmt.sprintf("i am an handle: %d", v))

65 Clone Or Not Clone, That Is The Question! func main() { var var1 int = 1 var var2 handle = 2 type handle int types(var1) types(var2) func types(val interface{) { switch v := val.(type) { case int: fmt.println(fmt.sprintf("i am an int: %d", v)) switch v := val.(type) { case handle: fmt.println(fmt.sprintf("i am an handle: %d", v))

66 Clone Or Not Clone, That Is The Question! func main() { var var1 int = 1 var var2 handle = 2 type handle = int types(var1) types(var2) func types(val interface{) { switch v := val.(type) { case int: fmt.println(fmt.sprintf("i am an int: %d", v)) switch v := val.(type) { case handle: fmt.println(fmt.sprintf("i am an handle: %d", v))

67 Clone Or Not Clone, That Is The Question! type Callable func() func test(callable Callable) { callable() func main() { mycallable := func() { fmt.println("callable") test(mycallable)

68 Clone Or Not Clone, That Is The Question! type Callable func() func main() { callable1 := func() { fmt.println("callable1") func test(val interface{) { switch v := val.(type) { case func(): var callable2 Callable callable2 = func() { fmt.println("callable2") v() default: fmt.println("wrong type") test(callable1) test(callable2)

69 He Looks Lazy, Isn t He?

70 He Looks Lazy, Isn t He? func main() { functions := make([]func(), 3) for i := 0; i < 3; i++ { functions[i] = func() { fmt.println(fmt.sprintf("iterator value: %d", i)) functions[0]() functions[1]() functions[2]()

71 He Looks Lazy, Isn t He? func main() { functions := make([]func(), 3) map instantiation for i := 0; i < 3; i++ { functions[i] = func() { fmt.println(fmt.sprintf("iterator value: %d", i)) functions[0]() functions[1]() functions[2]()

72 He Looks Lazy, Isn t He? func main() { functions := make([]func(), 3) for i := 0; i < 3; i++ { map instantiation loop functions[i] = func() { fmt.println(fmt.sprintf("iterator value: %d", i)) functions[0]() functions[1]() functions[2]()

73 He Looks Lazy, Isn t He? func main() { functions := make([]func(), 3) for i := 0; i < 3; i++ { functions[i] = func() { map instantiation loop closure fmt.println(fmt.sprintf("iterator value: %d", i)) functions[0]() functions[1]() functions[2]()

74 He Looks Lazy, Isn t He? func main() { functions := make([]func(), 3) for i := 0; i < 3; i++ { functions[i] = func() { fmt.println(fmt.sprintf("iterator value: %d", i)) functions[0]() functions[1]() functions[2]()

75 He Looks Lazy, Isn t He? func main() { functions := make([]func(), 3) for i := 0; i < 3; i++ { functions[i] = func(i int) func() { return func() { fmt.println(fmt.sprintf("iterator value: %d", i)) (i) functions[0]() functions[1]() functions[2]()

76 He Looks Lazy, Isn t He? func main() { functions := make([]func(), 3) for i := 0; i < 3; i++ { i := i functions[i] = func() { fmt.println(fmt.sprintf("iterator value: %d", i)) functions[0]() functions[1]() functions[2]()

77 Aren t We All A Little Bit Gopher?

78 Aren t We All A Little Bit Gopher? type Sortable interface { Sort(other Sortable)

79 Aren t We All A Little Bit Gopher? type Sortable interface { Sort(other Sortable) type MyStruct struct{ func (m MyStruct) Sort(other Sortable) {

80 Aren t We All A Little Bit Gopher? type Sortable interface { Sort(other Sortable) type MyStruct struct{ func (m MyStruct) Sort(other Sortable) { func main() { var foo Sortable = &MyStruct{ foo.sort(&mystruct{)

81 Aren t We All A Little Bit Gopher? type Sortable interface { Sort(other Sortable) type MyStruct struct{ func (m MyStruct) Sort(other Sortable) {

82 Aren t We All A Little Bit Gopher? type Sortable interface { Sort(other Sortable) type MyStruct struct{ func (m MyStruct) Sort(other Sortable) { var _ Sortable = MyStruct{ var _ Sortable = (*MyStruct)(nil)

83 It s Nil Or Nothing!

84 It s Nil Or Nothing! type MyError string func (m MyError) Error() string { return string(m)

85 It s Nil Or Nothing! type MyError string func (m MyError) Error() string { return string(m) type error interface { Error() string

86 It s Nil Or Nothing! type MyError string func (m MyError) Error() string { return string(m)

87 It s Nil Or Nothing! type MyError string func (m MyError) Error() string { return string(m) func test(v bool) error { var e *MyError = nil if v { return nil return e func main() { fmt.println(nil == test(true)) fmt.println(nil == test(false))

88 Seriously? I Don t Give A FAQ!

89 Seriously? I Don t Give A FAQ!

90 Remember Not Here To Scare You!

91 Remember Not Here To Scare You! But There Will Be Dragons

92 ? Questions???

93 ? Thank You??

Motivations History Principles Language Gommunity Success stories Conclusion. Let s Go! A brief introduction to Google s new language.

Motivations History Principles Language Gommunity Success stories Conclusion. Let s Go! A brief introduction to Google s new language. Let s Go! A brief introduction to Google s new language Aurélien Dumez Inria Bordeaux - Sud-Ouest aurelien.dumez@inria.fr Tuesday, October 2nd 2012 Content - 1/2 1 2 3 4 Characteristics SDK vs Examples