Going Loopy: Adventures in Iteration with Go

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

the conditional loop
Going Loopy slideshare.net/feyeleanor2

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])
}
}

package main
import "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
}
}
0: 0
1: 2
2: 4
3: 6
4: 8

package main
import "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
}
}

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

package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
for i := 0; i < len(s); i++ {
}
}

the inﬁnite loop

package main
import . "fmt"
func main() {
defer func() {
recover()
}()
s := []int{0, 2, 4, 6, 8}
var i int
for {
i++
}
}

package main
import . "fmt"
func main() {
defer func() {
recover()
}()
s := []int{0, 2, 4, 6, 8}
for i := 0; ; i++ {
}
}

the range

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

package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
}
}

a functional interlude

package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
func print_slice(s []int) {
}
}

package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
}
}

package main
import . "fmt"
func main() {
print_slice(0, 2, 4, 6, 8)
}
func print_slice(s ...int) {
}
}

asserting type

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) {
}
}

package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
}
}

package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
if s, ok := s.([]int); ok {
}
}
}

package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
}
}
}

package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
switch s := s.(type) {
case []int:
}
}
}

package main
import . "fmt"
func main() {
print_slice([]int{0, 2, 4, 6, 8})
}
case []int:
}
}
}

closures
54Going Loopy slideshare.net/feyeleanor/

package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_slice(func(i int) int { return s[i] })
}
case func(int) int:
for i := 0; i < 5; i++ {
Printf("%v: %vn", i, s(i))
}
}
}

package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
}
case func(int) int:
for i := 0; i < 5; i++ {
}
}
}

channels

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 {
i++
}
return
}

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)
}()
}
for v := range c {
i++
}
return
}

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)
}()
}
for v := range c {
i++
}
return
}

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)
}()
}
for v := range c {
i++
}
return
}

user-deﬁned type

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{}) {
i++
})
}

package main
import . "fmt"
}
f(v)
}
}
func main() {
}
i := 0
i++
})
}

package main
import . "fmt"
}
type IterableSlice []int
f(v)
}
}
func main() {
}
i := 0
i++
})
}

package main
import . "fmt"
}
f(v)
}
}
func main() {
}
i := 0
i++
})
}

package main
import . "fmt"
Each(f func(int, interface{}))
}
func (i IterableSlice) Each(f func(int, interface{})) {
for n, v := range i {
f(n, v)
}
}
func main() {
}
iter.Each(func(i int, v interface{}) {
})
}

package main
import . "fmt"
Each(interface{})
}
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{}) {
i++
})
s.Each(func(n int, v interface{}) {
Printf("%v: %vn", n, v)
})
}

package main
import . "fmt"
Each(interface{})
}
}
}
func main() {
i := 0
i++
})
})
}

upon reﬂection

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{}) {
case func(int) int:
for i := 0; i < 5; i++ {
}
case []int:
}
}
}

package main
import . "fmt"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
return s[i]
})
}
case func(int) int:
for i := 0; i < 5; i++ {
}
case []int:
}
}
}

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] })
}
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())
}
}
}

package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
}
case Func:
for i := 0; i < 5; i++ {
}
case Slice:
for i := 0; i < s.Len(); i++ {
}
}
}

package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
return s[i]
})
print_values(func(i int) (v int, ok bool) {
defer func() {
ok = recover() == nil
}()
v = s[i]
return
})
}
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())
}

package main
import . "fmt"
import . "reflect"
func main() {
s := []int{0, 2, 4, 6, 8}
print_values(s)
return s[i]
})
defer func() {
}()
v = s[i]
return
})
}
case Func:
print_func(s)
case Slice:
for i := 0; i < s.Len(); i++ {
}
}
}
case 1:
for i := 0; i < 5; i++ {
p[0] = ValueOf(i)
}
case 2:
print_value(i, v)
})
default:
}
}
var i int
r := s.Call(p)
for r[1].Bool() {
f(i, r[0])
i++
p[0] = ValueOf(i)
r = s.Call(p)
}
}
}

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

#golang

http://golang.org/

Going Loopy: Adventures in Iteration with Go

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