Things I learned teaching Go

Some thoughts about the difference between learning natural languages and programming languages, false friends, and hard stuff about interfaces.

Transcript

1. Things I learned teaching Go Francesc Campoy
2. Adoption
3. Making Go easy to learn - live workshops - online resources - the Go tour - blog posts - documentation - talks
4. Learning a new language
5. I caught a cold
6. estoy constipado
7. je suis … I am ...
8. False Friends
9. Java iterating over a collection for (Thing thing: things) Go iterating over a slice for thing := range things
10. Java iterating over a collection for (Thing thing: things) Go iterating over a slice for thing := range things
11. Java iterating over a collection for (Thing thing: things) Go iterating over a slice for _, thing := range things
13. “Like Yoda speaks code you must not”
14. Idiomatic Go code
15. Foreign influence
16. type Vertex struct { x, y int } func (this *Vertex) Abs() float64 { x, y := this.GetX(), this.GetY() return math.Sqrt(x*x + y*y) }
17. type Vertex struct { x, y int } func (this *Vertex) Abs() float64 { x, y := this.GetX(), this.GetY() return math.Sqrt(x*x + y*y) }
19. type Vertex struct { _x, _y int } func (self *Vertex) Abs() float64 { x, y := self._x, self._y return math.Sqrt(x*x + y*y) }
20. type Vertex struct { _x, _y int } func (self *Vertex) Abs() float64 { x, y := self._x, self._y return math.Sqrt(x*x + y*y) }
22. type Vertex struct { x, y int } func (v *Vertex) Abs() float64 { x, y := v.x, v.y return math.Sqrt(x*x + y*y) }
24. Things that are hard to learn
25. Eyjafjallajökull
27. Interfaces
28. type Stringer interface { String() string }
29. Set of constraints on types
30. type Stringer interface { String() string } type myCoolStringer interface { String() string }
31. type Reader interface { Read([]byte) (int, error) } type Writer interface { Write([]byte) (int, error) }
32. type ReadWriter interface { Reader Writer }
33. Reader gzip.Reader rand.Reader ReadWriter *os.File net.Conn
34. Reader gzip.Reader rand.Reader Writer gzip.Writer log.Writer ReadWriter *os.File net.Conn
35. Writer ReadWriter ??? Reader
36. interface{}
37. method set (I) ⊆ method set (T) Implicit satisfaction
38. Method sets
39. The method set of any other type T consists of all methods declared with receiver type T. The method set of a pointer type *T is the set of all methods declared with receiver *T or T. The method set of an interface type is its interface
40. The method set of any other type T consists of all methods declared with receiver type T. The method set of a pointer type *T is the set of all methods declared with receiver *T or T. The method set of an interface type is its interface
41. The method set of any other type T consists of all methods declared with receiver type T. The method set of a pointer type *T is the set of all methods declared with receiver *T or T. The method set of an interface type is its interface
42. type Person struct { Name string Age int } func (p *Person) String() string { return fmt.Sprintf("%s is %d", p.Name, p.Age) } func main() { p := &Person{"Hillary", 66} fmt.Println(p) }
43. type Person struct { Name string Age int } func (p *Person) String() string { return fmt.Sprintf("%s is %d", p.Name, p.Age) } func main() { p := &Person{"Hillary", 66} fmt.Println(p) }
44. Hillary is 66 years old
45. type Person struct { Name string Age int } func (p Person) String() string { return fmt.Sprintf("%s is %d", p.Name, p.Age) } func main() { p := &Person{"Hillary", 66} fmt.Println(p) }
46. Hillary is 66 years old
47. The method set of any other type T consists of all methods declared with receiver type T. The method set of a pointer type *T is the set of all methods declared with receiver *T or T. The method set of an interface type is its interface
48. type Person struct { Name string Age int } func (p Person) String() string { return fmt.Sprintf("%s is %d", p.Name, p.Age) } func main() { p := Person{"Hillary", 66} fmt.Println(p) }
49. Hillary is 66 years old
50. type Person struct { Name string Age int } func (p *Person) String() string { return fmt.Sprintf("%s is %d", p.Name, p.Age) } func main() { p := Person{"Hillary", 66} fmt.Println(p) }
51. {Hillary 66}
52. func (T) Foo() func (*T) Foo()
53. func (T) Foo() func (*T) Foo() T → T *T → *T
54. func (T) Foo() func (*T) Foo() T → T *T → *T *T → T
55. func (T) Foo() func (*T) Foo() T → T *T → *T *T → T T → *T
56. &42
57. func (T) Foo() func (*T) Foo() T → T *T → *T *T → T T ↛ *T
58. *T T func (T) Foo() func (T) Foo() func (*T) Foo()
60. nil
61. var s fmt.Stringer fmt.Println(s, s == nil) # <nil>, true
62. var p *Person var s fmt.Stringer = p fmt.Println(p, p == nil) fmt.Println(s, s == nil) # <nil> true # <nil> false
63. (type, value)
64. var p *Person var s fmt.Stringer = p fmt.Printf(“%#v”, s) # (*main.Person)(nil)
65. (*Person, nil) doesn’t equal nil
66. var s fmt.Stringer fmt.Printf(“%#v”, s) # <nil>
67. (nil, nil) equals nil
68. When nil is not nil
69. func do() error { var err *doError … return err } func main() { if err := do(); err != nil { fmt.Println(err) } }
70. func do() error { var err *doError … return err } func main() { if err := do(); err != nil { fmt.Println(err) } }
71. Other hard things
72. How do I learn Go?
73. read the specs often, really Know the basics
74. write code Immersion
75. share your code and ask for feedback Immersion
76. false friends and idioms Don’t be embarrassed
77. Always pass on what you have learned - Yoda
78. Adoption
79. @francesc Merci
80. - Eyjafjallajökull By Boaworm (Own work) CC-BY-3.0 via Wikimedia Commons - Yoda picture “Save you it can.” by JD Hancock is licensed under a Creative Commons Attribution 3.0 - Chinese letters by Michael Coghlan is licensed under a Creative Commons Attribution 3.0 Attributions