The document describes iterations and loops in Go using for loops and the range keyword. It discusses iterating over slices, using closures to iterate, and asserting types. Code examples are provided to demonstrate iterating over a slice of integers using a for loop with len() and indexing, using range to iterate, passing functions as arguments to iterate generically, and ensuring the type is correct when the argument is an interface.

1. going loopy
adventures in iteration with go
e.mchugh@inidsol.uk
Going Loopy slideshare.net/feyeleanor

2. the conditional loop
Going Loopy slideshare.net/feyeleanor2

3. package main
import "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
fmt.Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor3

4. package main
import "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
fmt.Printf("%v: %vn", i, s[i])
}
}
0: 0
1: 2
2: 4
3: 6
4: 8
Going Loopy slideshare.net/feyeleanor4

5. package main
import "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
fmt.Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor5

6. package main
import "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
fmt.Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor6

7. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
7Going Loopy slideshare.net/feyeleanor

8. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
8Going Loopy slideshare.net/feyeleanor

9. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
9Going Loopy slideshare.net/feyeleanor

10. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor10

11. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor11

12. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor12

13. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor13

14. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor14

15. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor15

16. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
16Going Loopy slideshare.net/feyeleanor

17. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor17

18. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor18

19. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor19

20. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor20

21. the infinite loop
Going Loopy slideshare.net/feyeleanor21

22. package main
import . "fmt"
func main() {
defer func() {
recover()
}()
s := []int{0, 2, 4, 6, 8}
var i int
for {
Printf("%v: %vn", i, s[i])
i++
}
}
Going Loopy slideshare.net/feyeleanor22

23. package main
import . "fmt"
func main() {
defer func() {
recover()
}()
s := []int{0, 2, 4, 6, 8}
var i int
for {
Printf("%v: %vn", i, s[i])
i++
}
}
Going Loopy slideshare.net/feyeleanor23

24. package main
import . "fmt"
func main() {
defer func() {
recover()
}()
s := []int{0, 2, 4, 6, 8}
var i int
for {
Printf("%v: %vn", i, s[i])
i++
}
}
Going Loopy slideshare.net/feyeleanor24

25. package main
import . "fmt"
func main() {
defer func() {
recover()
}()
s := []int{0, 2, 4, 6, 8}
var i int
for {
Printf("%v: %vn", i, s[i])
i++
}
}
Going Loopy slideshare.net/feyeleanor25

26. package main
import . "fmt"
func main() {
defer func() {
recover()
}()
s := []int{0, 2, 4, 6, 8}
var i int
for {
Printf("%v: %vn", i, s[i])
i++
}
}
Going Loopy slideshare.net/feyeleanor26

27. package main
import . "fmt"
func main() {
defer func() {
recover()
}()
s := []int{0, 2, 4, 6, 8}
var i int
for {
Printf("%v: %vn", i, s[i])
i++
}
}
Going Loopy slideshare.net/feyeleanor27

28. package main
import . "fmt"
func main() {
defer func() {
recover()
}()
s := []int{0, 2, 4, 6, 8}
for i := 0; ; i++ {
Printf("%v: %vn", i, s[i])
}
}
Going Loopy slideshare.net/feyeleanor28

29. the range
Going Loopy slideshare.net/feyeleanor29

30. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
Going Loopy slideshare.net/feyeleanor30

31. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
Going Loopy slideshare.net/feyeleanor31

32. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
Going Loopy slideshare.net/feyeleanor32

33. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
Going Loopy slideshare.net/feyeleanor33

34. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
Going Loopy slideshare.net/feyeleanor34

35. a functional interlude
35Going Loopy slideshare.net/feyeleanor

36. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s []int) {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
36Going Loopy slideshare.net/feyeleanor

37. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s []int) {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
37Going Loopy slideshare.net/feyeleanor

38. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s []int) {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
38Going Loopy slideshare.net/feyeleanor

39. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s []int) {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
39Going Loopy slideshare.net/feyeleanor

40. package main
import . "fmt"
func main() {
print_slice(0, 2, 4, 6, 8)
}
func print_slice(s ...int) {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
40Going Loopy slideshare.net/feyeleanor

41. package main
import . "fmt"
func main() {
print_slice(0, 2, 4, 6, 8)
}
func print_slice(s ...int) {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
41Going Loopy slideshare.net/feyeleanor

42. asserting type
Going Loopy slideshare.net/feyeleanor42

43. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
for i, v := range s.([]int) {
Printf("%v: %vn", i, v)
}
}
Going Loopy slideshare.net/feyeleanor43

44. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
for i, v := range s.([]int) {
Printf("%v: %vn", i, v)
}
}
Going Loopy slideshare.net/feyeleanor44

45. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
for i, v := range s.([]int) {
Printf("%v: %vn", i, v)
}
}
Going Loopy slideshare.net/feyeleanor45

46. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
if s, ok := s.([]int); ok {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
Going Loopy slideshare.net/feyeleanor46

47. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
if s, ok := s.([]int); ok {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
Going Loopy slideshare.net/feyeleanor47

48. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
if s, ok := s.([]int); ok {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
Going Loopy slideshare.net/feyeleanor48

49. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
if s, ok := s.([]int); ok {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
Going Loopy slideshare.net/feyeleanor49

50. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
if s, ok := s.([]int); ok {
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
Going Loopy slideshare.net/feyeleanor50

51. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
switch s := s.(type) {
case []int:
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
Going Loopy slideshare.net/feyeleanor51

52. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
switch s := s.(type) {
case []int:
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
Going Loopy slideshare.net/feyeleanor52

53. package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s interface{}) {
switch s := s.(type) {
case []int:
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
Going Loopy slideshare.net/feyeleanor53

54. closures
54Going Loopy slideshare.net/feyeleanor/

55. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_slice(func(i int) int { return s[i] })
}
func print_slice(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
}
}
55Going Loopy slideshare.net/feyeleanor

56. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_slice(func(i int) int { return s[i] })
}
func print_slice(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
}
}
56Going Loopy slideshare.net/feyeleanor

57. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_slice(func(i int) int { return s[i] })
}
func print_slice(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
}
}
57Going Loopy slideshare.net/feyeleanor

58. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_slice(func(i int) int { return s[i] })
}
func print_slice(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
}
}
58Going Loopy slideshare.net/feyeleanor

59. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_slice(func(i int) int { return s[i] })
}
func print_slice(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
}
}
59Going Loopy slideshare.net/feyeleanor

60. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_slice(func(i int) int { return s[i] })
}
func print_slice(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
}
}
60Going Loopy slideshare.net/feyeleanor

61. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_slice(func(i int) int { return s[i] })
}
func print_slice(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
}
}
61Going Loopy slideshare.net/feyeleanor

62. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_slice(func(i int) int { return s[i] })
}
func print_slice(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
}
}
62Going Loopy slideshare.net/feyeleanor

63. channels
63Going Loopy slideshare.net/feyeleanor

64. package main
import . "fmt"
func main() {
c := make(chan int)
go func() {
for _, v := range []int{0, 2, 4, 6, 8} {
c <- v
}
close(c)
}()
Printf("elements: %vn", print_channel(c))
}
func print_channel(c chan int) (i int) {
for v := range c {
Printf("%v: %vn", i, v)
i++
}
return
}
64Going Loopy slideshare.net/feyeleanor

65. package main
import . "fmt"
func main() {
c := make(chan int)
go func() {
for _, v := range []int{0, 2, 4, 6, 8} {
c <- v
}
close(c)
}()
Printf("elements: %vn", print_channel(c))
}
func print_channel(c chan int) (i int) {
for v := range c {
Printf("%v: %vn", i, v)
i++
}
return
}
65Going Loopy slideshare.net/feyeleanor

66. package main
import . "fmt"
func main() {
c := make(chan int, 16)
go func() {
for _, v := range []int{0, 2, 4, 6, 8} {
c <- v
}
close(c)
}()
Printf("elements: %vn", print_channel(c))
}
func print_channel(c chan int) (i int) {
for v := range c {
Printf("%v: %vn", i, v)
i++
}
return
}
66Going Loopy slideshare.net/feyeleanor

67. package main
import . "fmt"
func main() {
c := make(chan int)
go func() {
for _, v := range []int{0, 2, 4, 6, 8} {
c <- v
}
close(c)
}()
Printf("elements: %vn", print_channel(c))
}
func print_channel(c chan int) (i int) {
for v := range c {
Printf("%v: %vn", i, v)
i++
}
return
}
67Going Loopy slideshare.net/feyeleanor

68. package main
import . "fmt"
func main() {
c := make(chan int)
go func() {
for _, v := range []int{0, 2, 4, 6, 8} {
c <- v
}
close(c)
}()
Printf("elements: %vn", print_channel(c))
}
func print_channel(c chan int) (i int) {
for v := range c {
Printf("%v: %vn", i, v)
i++
}
return
}
68Going Loopy slideshare.net/feyeleanor

69. package main
import . "fmt"
func main() {
c := make(chan int)
go func() {
for _, v := range []int{0, 2, 4, 6, 8} {
c <- v
}
close(c)
}()
Printf("elements: %vn", print_channel(c))
}
func print_channel(c chan int) (i int) {
for v := range c {
Printf("%v: %vn", i, v)
i++
}
return
}
69Going Loopy slideshare.net/feyeleanor

70. package main
import . "fmt"
func main() {
c := make(chan int)
go func() {
for _, v := range []int{0, 2, 4, 6, 8} {
c <- v
}
close(c)
}()
Printf("elements: %vn", print_channel(c))
}
func print_channel(c chan int) (i int) {
for v := range c {
Printf("%v: %vn", i, v)
i++
}
return
}
70Going Loopy slideshare.net/feyeleanor

71. package main
import . "fmt"
func main() {
c := make(chan int)
go func() {
for _, v := range []int{0, 2, 4, 6, 8} {
c <- v
}
close(c)
}()
Printf("elements: %vn", print_channel(c))
}
func print_channel(c chan int) (i int) {
for v := range c {
Printf("%v: %vn", i, v)
i++
}
return
}
71Going Loopy slideshare.net/feyeleanor

72. package main
import . "fmt"
func main() {
c := make(chan int)
go func() {
for _, v := range []int{0, 2, 4, 6, 8} {
c <- v
}
close(c)
}()
Printf("elements: %vn", print_channel(c))
}
func print_channel(c chan int) (i int) {
for v := range c {
Printf("%v: %vn", i, v)
i++
}
return
}
72Going Loopy slideshare.net/feyeleanor

73. package main
import . "fmt"
func main() {
c := make(chan int)
go func() {
for _, v := range []int{0, 2, 4, 6, 8} {
c <- v
}
close(c)
}()
Printf("elements: %vn", print_channel(c))
}
func print_channel(c chan int) (i int) {
for v := range c {
Printf("%v: %vn", i, v)
i++
}
return
}
73Going Loopy slideshare.net/feyeleanor

74. user-defined type
74Going Loopy slideshare.net/feyeleanor

75. package main
import . "fmt"
type Iterable interface {
Each(func(interface{}))
}
type IterableSlice[]int
func (i IterableSlice) Each(f func(interface{})) {
for _, v := range i {
f(v)
}
}
func main() {
print_values(IterableSlice{ 0, 2, 4, 6, 8 })
}
func print_values(iter Iterable) {
i := 0
iter.Each(func(v interface{}) {
Printf("%v: %vn", i, v)
i++
})
}
75Going Loopy slideshare.net/feyeleanor

76. package main
import . "fmt"
type Iterable interface {
Each(func(interface{}))
}
type IterableSlice[]int
func (i IterableSlice) Each(f func(interface{})) {
for _, v := range i {
f(v)
}
}
func main() {
print_values(IterableSlice{ 0, 2, 4, 6, 8 })
}
func print_values(iter Iterable) {
i := 0
iter.Each(func(v interface{}) {
Printf("%v: %vn", i, v)
i++
})
}
76Going Loopy slideshare.net/feyeleanor

77. package main
import . "fmt"
type Iterable interface {
Each(func(interface{}))
}
type IterableSlice[]int
func (i IterableSlice) Each(f func(interface{})) {
for _, v := range i {
f(v)
}
}
func main() {
print_values(IterableSlice{ 0, 2, 4, 6, 8 })
}
func print_values(iter Iterable) {
i := 0
iter.Each(func(v interface{}) {
Printf("%v: %vn", i, v)
i++
})
}
77Going Loopy slideshare.net/feyeleanor

78. package main
import . "fmt"
type Iterable interface {
Each(func(interface{}))
}
type IterableSlice []int
func (i IterableSlice) Each(f func(interface{})) {
for _, v := range i {
f(v)
}
}
func main() {
print_values(IterableSlice{ 0, 2, 4, 6, 8 })
}
func print_values(iter Iterable) {
i := 0
iter.Each(func(v interface{}) {
Printf("%v: %vn", i, v)
i++
})
}
78Going Loopy slideshare.net/feyeleanor

79. package main
import . "fmt"
type Iterable interface {
Each(func(interface{}))
}
type IterableSlice []int
func (i IterableSlice) Each(f func(interface{})) {
for _, v := range i {
f(v)
}
}
func main() {
print_values(IterableSlice{ 0, 2, 4, 6, 8 })
}
func print_values(iter Iterable) {
i := 0
iter.Each(func(v interface{}) {
Printf("%v: %vn", i, v)
i++
})
}
79Going Loopy slideshare.net/feyeleanor

80. package main
import . "fmt"
type Iterable interface {
Each(func(interface{}))
}
type IterableSlice []int
func (i IterableSlice) Each(f func(interface{})) {
for _, v := range i {
f(v)
}
}
func main() {
print_values(IterableSlice{ 0, 2, 4, 6, 8 })
}
func print_values(iter Iterable) {
i := 0
iter.Each(func(v interface{}) {
Printf("%v: %vn", i, v)
i++
})
}
80Going Loopy slideshare.net/feyeleanor

81. package main
import . "fmt"
type Iterable interface {
Each(func(interface{}))
}
type IterableSlice []int
func (i IterableSlice) Each(f func(interface{})) {
for _, v := range i {
f(v)
}
}
func main() {
print_values(IterableSlice{ 0, 2, 4, 6, 8 })
}
func print_values(iter Iterable) {
i := 0
iter.Each(func(v interface{}) {
Printf("%v: %vn", i, v)
i++
})
}
81Going Loopy slideshare.net/feyeleanor

82. package main
import . "fmt"
type Iterable interface {
Each(f func(int, interface{}))
}
type IterableSlice []int
func (i IterableSlice) Each(f func(int, interface{})) {
for n, v := range i {
f(n, v)
}
}
func main() {
print_values(IterableSlice{ 0, 2, 4, 6, 8 })
}
func print_values(iter Iterable) {
iter.Each(func(i int, v interface{}) {
Printf("%v: %vn", i, v)
})
}
82Going Loopy slideshare.net/feyeleanor

83. package main
import . "fmt"
type Iterable interface {
Each(interface{})
}
type IterableSlice []int
func (i IterableSlice) Each(f interface{}) {
switch f := f.(type) {
case func(interface{}):
for _, v := range i { f(v) }
case func(int, interface{}):
for n, v := range i { f(n, v) }
}
}
func main() {
s := IterableSlice{ 0, 2, 4, 6, 8 }
i := 0
s.Each(func(v interface{}) {
Printf("%v: %vn", i, v)
i++
})
s.Each(func(n int, v interface{}) {
Printf("%v: %vn", n, v)
})
}
83Going Loopy slideshare.net/feyeleanor

84. package main
import . "fmt"
type Iterable interface {
Each(interface{})
}
type IterableSlice []int
func (i IterableSlice) Each(f interface{}) {
switch f := f.(type) {
case func(interface{}):
for _, v := range i { f(v) }
case func(int, interface{}):
for n, v := range i { f(n, v) }
}
}
func main() {
s := IterableSlice{ 0, 2, 4, 6, 8 }
i := 0
s.Each(func(v interface{}) {
Printf("%v: %vn", i, v)
i++
})
s.Each(func(n int, v interface{}) {
Printf("%v: %vn", n, v)
})
}
84Going Loopy slideshare.net/feyeleanor

85. package main
import . "fmt"
type Iterable interface {
Each(interface{})
}
type IterableSlice []int
func (i IterableSlice) Each(f interface{}) {
switch f := f.(type) {
case func(interface{}):
for _, v := range i { f(v) }
case func(int, interface{}):
for n, v := range i { f(n, v) }
}
}
func main() {
s := IterableSlice{ 0, 2, 4, 6, 8 }
i := 0
s.Each(func(v interface{}) {
Printf("%v: %vn", i, v)
i++
})
s.Each(func(n int, v interface{}) {
Printf("%v: %vn", n, v)
})
}
85Going Loopy slideshare.net/feyeleanor

86. upon reflection
86Going Loopy slideshare.net/feyeleanor

87. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
}
func print_values(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
case []int:
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
87Going Loopy slideshare.net/feyeleanor

88. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
}
func print_values(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
case []int:
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
88Going Loopy slideshare.net/feyeleanor

89. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
}
func print_values(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
case []int:
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
89Going Loopy slideshare.net/feyeleanor

90. package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
}
func print_values(s interface{}) {
switch s := s.(type) {
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
case []int:
for i, v := range s {
Printf("%v: %vn", i, v)
}
}
}
90Going Loopy slideshare.net/feyeleanor

91. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int { return s[i] })
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
for i := 0; i < 5; i++ {
p := []Value{ ValueOf(i) }
Printf("%v: %vn", i, s.Call(p)[0].Interface())
}
case Slice:
for i := 0; i < s.Len(); i++ {
Printf("%v: %vn", i, s.Index(i).Interface())
}
}
}
91Going Loopy slideshare.net/feyeleanor

92. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int { return s[i] })
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
for i := 0; i < 5; i++ {
p := []Value{ ValueOf(i) }
Printf("%v: %vn", i, s.Call(p)[0].Interface())
}
case Slice:
for i := 0; i < s.Len(); i++ {
Printf("%v: %vn", i, s.Index(i).Interface())
}
}
}
92Going Loopy slideshare.net/feyeleanor

93. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int { return s[i] })
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
for i := 0; i < 5; i++ {
p := []Value{ ValueOf(i) }
Printf("%v: %vn", i, s.Call(p)[0].Interface())
}
case Slice:
for i := 0; i < s.Len(); i++ {
Printf("%v: %vn", i, s.Index(i).Interface())
}
}
}
93Going Loopy slideshare.net/feyeleanor

94. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int { return s[i] })
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
for i := 0; i < 5; i++ {
p := []Value{ ValueOf(i) }
Printf("%v: %vn", i, s.Call(p)[0].Interface())
}
case Slice:
for i := 0; i < s.Len(); i++ {
Printf("%v: %vn", i, s.Index(i).Interface())
}
}
}
94Going Loopy slideshare.net/feyeleanor

95. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int { return s[i] })
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
for i := 0; i < 5; i++ {
p := []Value{ ValueOf(i) }
Printf("%v: %vn", i, s.Call(p)[0].Interface())
}
case Slice:
for i := 0; i < s.Len(); i++ {
Printf("%v: %vn", i, s.Index(i).Interface())
}
}
}
95Going Loopy slideshare.net/feyeleanor

96. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
print_values(func(i int) (v int, ok bool) {
defer func() {
ok = recover() == nil
}()
v = s[i]
return
})
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
print_func(s)
case Slice:
for i := 0; i < s.Len(); i++ {
print_value(i, s.Index(i))
}
}
}
func print_func(s Value) {
switch s.Type().NumOut() {
case 1:
p := make([]Value, 1)
for i := 0; i < 5; i++ {
p[0] = ValueOf(i)
print_value(i, s.Call(p)[0])
}
case 2:
each(s, func(i int, v Value) {
print_value(i, v)
})
default:
panic(s.Interface())
}
}
func each(s Value, f func(int, Value)) {
var i int
p := []Value{ ValueOf(0) }
r := s.Call(p)
for r[1].Bool() {
f(i, r[0])
i++
p[0] = ValueOf(i)
r = s.Call(p)
}
}
func print_value(i int, v Value) {
Printf("%v: %vn", i, v.Interface())
}
96Going Loopy slideshare.net/feyeleanor

97. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
print_values(func(i int) (v int, ok bool) {
defer func() {
ok = recover() == nil
}()
v = s[i]
return
})
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
print_func(s)
case Slice:
for i := 0; i < s.Len(); i++ {
print_value(i, s.Index(i))
}
}
}
func print_func(s Value) {
switch s.Type().NumOut() {
case 1:
p := make([]Value, 1)
for i := 0; i < 5; i++ {
p[0] = ValueOf(i)
print_value(i, s.Call(p)[0])
}
case 2:
each(s, func(i int, v Value) {
print_value(i, v)
})
default:
panic(s.Interface())
}
}
func each(s Value, f func(int, Value)) {
var i int
p := []Value{ ValueOf(0) }
r := s.Call(p)
for r[1].Bool() {
f(i, r[0])
i++
p[0] = ValueOf(i)
r = s.Call(p)
}
}
func print_value(i int, v Value) {
Printf("%v: %vn", i, v.Interface())
}
97Going Loopy slideshare.net/feyeleanor

98. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
print_values(func(i int) (v int, ok bool) {
defer func() {
ok = recover() == nil
}()
v = s[i]
return
})
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
print_func(s)
case Slice:
for i := 0; i < s.Len(); i++ {
print_value(i, s.Index(i))
}
}
}
func print_func(s Value) {
switch s.Type().NumOut() {
case 1:
p := make([]Value, 1)
for i := 0; i < 5; i++ {
p[0] = ValueOf(i)
print_value(i, s.Call(p)[0])
}
case 2:
each(s, func(i int, v Value) {
print_value(i, v)
})
default:
panic(s.Interface())
}
}
func each(s Value, f func(int, Value)) {
var i int
p := []Value{ ValueOf(0) }
r := s.Call(p)
for r[1].Bool() {
f(i, r[0])
i++
p[0] = ValueOf(i)
r = s.Call(p)
}
}
func print_value(i int, v Value) {
Printf("%v: %vn", i, v.Interface())
}
98Going Loopy slideshare.net/feyeleanor

99. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
print_values(func(i int) (v int, ok bool) {
defer func() {
ok = recover() == nil
}()
v = s[i]
return
})
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
print_func(s)
case Slice:
for i := 0; i < s.Len(); i++ {
print_value(i, s.Index(i))
}
}
}
func print_func(s Value) {
switch s.Type().NumOut() {
case 1:
p := make([]Value, 1)
for i := 0; i < 5; i++ {
p[0] = ValueOf(i)
print_value(i, s.Call(p)[0])
}
case 2:
each(s, func(i int, v Value) {
print_value(i, v)
})
default:
panic(s.Interface())
}
}
func each(s Value, f func(int, Value)) {
var i int
p := []Value{ ValueOf(0) }
r := s.Call(p)
for r[1].Bool() {
f(i, r[0])
i++
p[0] = ValueOf(i)
r = s.Call(p)
}
}
func print_value(i int, v Value) {
Printf("%v: %vn", i, v.Interface())
}
99Going Loopy slideshare.net/feyeleanor

100. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
print_values(func(i int) (v int, ok bool) {
defer func() {
ok = recover() == nil
}()
v = s[i]
return
})
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
print_func(s)
case Slice:
for i := 0; i < s.Len(); i++ {
print_value(i, s.Index(i))
}
}
}
func print_func(s Value) {
switch s.Type().NumOut() {
case 1:
p := make([]Value, 1)
for i := 0; i < 5; i++ {
p[0] = ValueOf(i)
print_value(i, s.Call(p)[0])
}
case 2:
each(s, func(i int, v Value) {
print_value(i, v)
})
default:
panic(s.Interface())
}
}
func each(s Value, f func(int, Value)) {
var i int
p := []Value{ ValueOf(0) }
r := s.Call(p)
for r[1].Bool() {
f(i, r[0])
i++
p[0] = ValueOf(i)
r = s.Call(p)
}
}
func print_value(i int, v Value) {
Printf("%v: %vn", i, v.Interface())
}
100Going Loopy slideshare.net/feyeleanor

101. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
print_values(func(i int) (v int, ok bool) {
defer func() {
ok = recover() == nil
}()
v = s[i]
return
})
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
print_func(s)
case Slice:
for i := 0; i < s.Len(); i++ {
print_value(i, s.Index(i))
}
}
}
func print_func(s Value) {
switch s.Type().NumOut() {
case 1:
p := make([]Value, 1)
for i := 0; i < 5; i++ {
p[0] = ValueOf(i)
print_value(i, s.Call(p)[0])
}
case 2:
each(s, func(i int, v Value) {
print_value(i, v)
})
default:
panic(s.Interface())
}
}
func each(s Value, f func(int, Value)) {
var i int
p := []Value{ ValueOf(0) }
r := s.Call(p)
for r[1].Bool() {
f(i, r[0])
i++
p[0] = ValueOf(i)
r = s.Call(p)
}
}
func print_value(i int, v Value) {
Printf("%v: %vn", i, v.Interface())
}
101Going Loopy slideshare.net/feyeleanor

102. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
print_values(func(i int) (v int, ok bool) {
defer func() {
ok = recover() == nil
}()
v = s[i]
return
})
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
print_func(s)
case Slice:
for i := 0; i < s.Len(); i++ {
print_value(i, s.Index(i))
}
}
}
func print_func(s Value) {
switch s.Type().NumOut() {
case 1:
p := make([]Value, 1)
for i := 0; i < 5; i++ {
p[0] = ValueOf(i)
print_value(i, s.Call(p)[0])
}
case 2:
each(s, func(i int, v Value) {
print_value(i, v)
})
default:
panic(s.Interface())
}
}
func each(s Value, f func(int, Value)) {
var i int
p := []Value{ ValueOf(0) }
r := s.Call(p)
for r[1].Bool() {
f(i, r[0])
i++
p[0] = ValueOf(i)
r = s.Call(p)
}
}
func print_value(i int, v Value) {
Printf("%v: %vn", i, v.Interface())
}
102Going Loopy slideshare.net/feyeleanor

103. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
print_values(func(i int) (v int, ok bool) {
defer func() {
ok = recover() == nil
}()
v = s[i]
return
})
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
print_func(s)
case Slice:
for i := 0; i < s.Len(); i++ {
print_value(i, s.Index(i))
}
}
}
func print_func(s Value) {
switch s.Type().NumOut() {
case 1:
p := make([]Value, 1)
for i := 0; i < 5; i++ {
p[0] = ValueOf(i)
print_value(i, s.Call(p)[0])
}
case 2:
each(s, func(i int, v Value) {
print_value(i, v)
})
default:
panic(s.Interface())
}
}
func each(s Value, f func(int, Value)) {
var i int
p := []Value{ ValueOf(0) }
r := s.Call(p)
for r[1].Bool() {
f(i, r[0])
i++
p[0] = ValueOf(i)
r = s.Call(p)
}
}
func print_value(i int, v Value) {
Printf("%v: %vn", i, v.Interface())
}
103Going Loopy slideshare.net/feyeleanor

104. package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
print_values(func(i int) int {
return s[i]
})
print_values(func(i int) (v int, ok bool) {
defer func() {
ok = recover() == nil
}()
v = s[i]
return
})
}
func print_values(s interface{}) {
switch s := ValueOf(s); s.Kind() {
case Func:
print_func(s)
case Slice:
for i := 0; i < s.Len(); i++ {
print_value(i, s.Index(i))
}
}
}
func print_func(s Value) {
switch s.Type().NumOut() {
case 1:
p := make([]Value, 1)
for i := 0; i < 5; i++ {
p[0] = ValueOf(i)
print_value(i, s.Call(p)[0])
}
case 2:
each(s, func(i int, v Value) {
print_value(i, v)
})
default:
panic(s.Interface())
}
}
func each(s Value, f func(int, Value)) {
var i int
p := []Value{ ValueOf(0) }
r := s.Call(p)
for r[1].Bool() {
f(i, r[0])
i++
p[0] = ValueOf(i)
r = s.Call(p)
}
}
func print_value(i int, v Value) {
Printf("%v: %vn", i, v.Interface())
}
104Going Loopy slideshare.net/feyeleanor

105. you now know go
Going Loopy 112 slideshare.net/feyeleanor

106. #golang
Going Loopy 113 slideshare.net/feyeleanor

107. http://golang.org/
Going Loopy 114 slideshare.net/feyeleanor