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RubyConf Portugal 2014 - Why ruby must go!

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Gautam Rege
Gautam Rege

The document discusses the Go programming language and how it differs from Ruby. It provides examples of Go code demonstrating type declarations, embedded types, exported variables and functions, and variable redeclaration. It also discusses some concepts in Go like interfaces, channels, and concurrency that are different from Ruby. The document suggests that Go teaches programmers awareness about variables, types, and errors that can improve Ruby code.

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Why Ruby Must Go!
Why must Ruby go?
Why must Ruby go?
Why Ruby Must Go! What can Ruby incorporate from Go? What is Programmer Awareness? As a Rubyist, what does Go teach me?
@gautamrege @joshsoftware ! @rubyconfindia
Programming Paradigms Imperative Declarative Procedural Functional Object Oriented Symbolic
Programming Paradigms Imperative Declarative Procedural Functional Object Oriented Symbolic C++! Java! Python! Ruby Order of execution / steps One or more subroutines
Programming Paradigms Imperative Declarative Procedural Order of execution / steps One or more subroutines Functional Object Oriented Symbolic Pascal! FORTRAN! C
Programming Paradigms Imperative Declarative Procedural Order of execution / steps One or more subroutines Functional Object Oriented Symbolic Pascal! FORTRAN! C! Go
Go Lang C on Steroids
Go Lang C on Steroids
Go Lang C on Steroids • No more memory leaks. (Garbage collection)
Go Lang C on Steroids • No more memory leaks. (Garbage collection) • No more pointer de-referencing. (-> or . )
Go Lang C on Steroids • No more memory leaks. (Garbage collection) • No more pointer de-referencing. (-> or . ) • Support for maps, slices and channels.
Go Lang C on Steroids • No more memory leaks. (Garbage collection) • No more pointer de-referencing. (-> or . ) • Support for maps, slices and channels. • Support for closures.
Go Lang C on Steroids • No more memory leaks. (Garbage collection) • No more pointer de-referencing. (-> or . ) • Support for maps, slices and channels. • Support for closures. • Concurrency: closures, channels & go-routines.
Go is different !
Go is different !
Go is different ! • No exceptions, only errors.
Go is different ! • No exceptions, only errors. • Return multiple values from functions
Go is different ! • No exceptions, only errors. • Return multiple values from functions • Interfaces but no classes (only structs)
Go is different ! • No exceptions, only errors. • Return multiple values from functions • Interfaces but no classes (only structs) • No inheritance but embedded structs
Let’s get Going And learn Go along the way!
Duck Typing in Ruby
Duck Typing in Ruby Programming convenience.! Implicit Type Conversions.! No complex Type Inference
Duck Typing in Ruby Programming convenience.! Implicit Type Conversions.! No complex Type Inference Don’t fight the Type System
Duck Typing in Ruby Programming convenience.! Implicit Type Conversions.! No complex Type Inference Don’t fight the Type System Code First - Resolve Issues Later
Problems with Duck Typing
Problems with Duck Typing No Early Warning System! Reactive programming! Compiler Time checks!
Problems with Duck Typing No Early Warning System! Reactive programming! Compiler Time checks! Type Inference
Problems with Duck Typing No Early Warning System! Reactive programming! Compiler Time checks! Type Inference Code Once Correctly
Types? Who cares? We’re ! Rubyists!
Types? Who cares? We’re ! Rubyists!
Type Checks in Ruby! def convert_hashes_to_parameters(key, value, assign_if_converted=true)! converted = convert_value_to_parameters(value)! #...! end! ! def convert_value_to_parameters(value)! if value.is_a?(Array) && !converted_arrays.member?(value)! #...! converted_arrays << converted! converted! elsif value.is_a?(Parameters) || !value.is_a?(Hash)! #...! end! end
Type Checks in Ruby! def convert_hashes_to_parameters(key, value, assign_if_converted=true)! converted = convert_value_to_parameters(value)! #...! end! ! def convert_value_to_parameters(value)! if value.is_a?(Array) && !converted_arrays.member?(value)! #...! converted_arrays << converted! converted! elsif value.is_a?(Parameters) || !value.is_a?(Hash)! #...! end! end
Type Checks in Ruby! def convert_hashes_to_parameters(key, value, assign_if_converted=true)! converted = convert_value_to_parameters(value)! #...! end! ! def convert_value_to_parameters(value)! if value.is_a?(Array) && !converted_arrays.member?(value)! #...! converted_arrays << converted! converted! elsif value.is_a?(Parameters) || !value.is_a?(Hash)! #...! end! end def permit!! each_pair do |key, value|! value = convert_hashes_to_parameters(key, value)! #...! end
Type Checks in Ruby! def convert_hashes_to_parameters(key, value, assign_if_converted=true)! converted = convert_value_to_parameters(value)! #...! end! ! def convert_value_to_parameters(value)! if value.is_a?(Array) && !converted_arrays.member?(value)! #...! converted_arrays << converted! converted! elsif value.is_a?(Parameters) || !value.is_a?(Hash)! #...! end! end def permit!! each_pair do |key, value|! value = convert_hashes_to_parameters(key, value)! #...! end Strong Parameters!
To Duck or to Type
To Duck or to Type Best of Both worlds
To Duck or to Type Light weight 1-level Type check
To Duck or to Type Light weight 1-level Type check type point int ! func main() { var i int = 2 var j point = 2 ! i == j }
To Duck or to Type Light weight 1-level Type check type point int ! func main() { var i int = 2 var j point = 2 Variable name first, then the type ! i == j }
To Duck or to Type Light weight 1-level Type check type point int ! func main() { var i int = 2 var j point = 2 ! i == j }
To Duck or to Type Light weight 1-level Type check type point int ! func main() { var i int = 2 var j point = 2 ! i == j } Error: invalid operation: i == j (mismatched types int and point)
Ruby re-defines Object Oriented Concepts, Go re-defines programming itself! “ ”
Programmer Awareness
Programmer Awareness %QORKNGT
Programmer Awareness %QORKNGT 4GXKGYGT
Programmer Awareness %QORKNGT 4GXKGYGT (TCOGYQTM
Programmer Awareness %QORKNGT 4GXKGYGT (TCOGYQTM .CPIWCIG
Programmer Awareness Variable declaration and assignment
Programmer Awareness Variable declaration and assignment y y
Programmer Awareness Variable declaration and assignment y := 2 // y is of type int! y = "3" Implicit declaration
Programmer Awareness Variable declaration and assignment y := 2 // y is of type int! y = "3" Assignment
Programmer Awareness Variable declaration and assignment y := 2 // y is of type int! y = "3" COMPLIER ERROR! cannot use “3” (type string) as type int in assignment
Programmer ERROR? Variable declaration and assignment y := 2 // y is of type int! y = "3" As a programmer, we probably re-assigned “y” to a String by mistake!
Programmer AWARENESS Variable declaration and assignment y := 2 // y is of type int! y, _ = strconv.Atoi("3") There’s always a right way to do things!
! Eh… what?
! Eh… what? https://flic.kr/p/mnZgQw
Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! }
Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! } import packages
Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! } Exported function
Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! }
Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! } I’m practical. You can re-declare err in your code!* * Conditions apply
Programmer Awareness Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! }
Programmer Awareness Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! f, err := f.Stat()! }
Programmer Awareness Variable Re-declaration import "os"! Error: no new ! variables on left func main() {! side of := ! f, err := os.Open("somefile")! ! // handle error! ! ! f, err := f.Stat()! } Hmm.. I think you re-used the variable f by mistake!
Programmer Awareness Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! f, err = f.Open("other file")! } Re-assign ! explicitly.. 
With Great Power Comes Great Responsibility
https://flic.kr/p/kSSWb
Overloading but first …
Lets Go a little more! type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Dimensions)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } Type Declaration
Lets Go a little more! type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Dimensions)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } Exported Array
Lets Go a little more! type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Dimensions)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } Exported Array The size in Array is part of the type! [2]float32 != [3]float32
Lets Go a little more! type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Dimensions)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } Embedding! (Not inheritance)
Lets Go a little more! type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Dimensions)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } hotel.Dimensions and not hotel.Hall.Dimensions
Lets Go a little more! func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } Dimensions)!
Lets Go a little more! func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! }
Programmer Awareness type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! }
Programmer Awareness type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } Which Name should I use? Error: Ambiguous selector hotel.Name!
Programmer Awareness type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Name)Hall.! Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! }
Programmer Awareness type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Hall.Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! }
Modules in Ruby module Layout! def manager! p "Layout Manager"! end! end! ! module Hall! def manager! p "Hall Manager"! end! end! ! class Hotel! include Layout! include Hall! end def main! hotel = Hotel.new! p hotel.manager! end
Modules in Ruby module Layout! def manager! p "Layout Manager"! end! end! ! module Hall! def manager! p "Hall Manager"! end! end! ! class Hotel! include Layout! include Hall! end def main! hotel = Hotel.new! p hotel.manager! end Which language is this dude?
Include modules in order! https://flic.kr/p/e7SnAa
Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! }
Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! } Map of strings and Hotels
Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! } Easy iteration syntax!
Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! } Blank Identifier - ignore value
Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! }
Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! } Bad practice! ! I’ll randomise the order!
Ordered Hashes!
Ordered Hashes!
Pushing some Goodies into Ruby https://flic.kr/p/awu6ZA
Defer mu sync.Mutex! ! func foo() {! mu.Lock()! defer mu.unLock()! // do something...! } https://flic.kr/p/awu6ZA
Defer func trace(s string) { fmt.Println("entering:", s) }! func untrace(s string) { fmt.Println("leaving:", s) }! ! func a() {! trace("a")! defer untrace("a")! // do something....! } https://flic.kr/p/awu6ZA
Concurrency Parallelism Multi-core Processing https://flic.kr/p/awu6ZA
Example - Relay Race • 4 legs of the race • Each leg does processing concurrently. • Completion should be in order. (pass the baton)
Concurrent Example Leg 1 Leg 2 Leg 3 Leg 4
Concurrent Processing Leg 1 Leg 2 Leg 3 Leg 4 CPU churn - CPU time consuming operation.
Completion Order Leg 1 Leg 2 Leg 3 Leg 4
Completion Order Leg 1 Leg 2 Leg 3 Leg 4
Completion Order Leg 1 Leg 2 Leg 3 Leg 4
Completion Order Leg 1 Leg 2 Leg 3 Leg 4
CSP! Communicating Sequential Processes https://flic.kr/p/6MwYFo https://flic.kr/p/awu6ZA
CSP! Communicating Sequential Processes since 1978 !! https://flic.kr/p/awu6ZA https://flic.kr/p/6MwYFo
package main ! import ( "fmt" "runtime" "sync" ) ! var wg sync.WaitGroup ! /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() }
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) ! for i := 1; i < 5; i++ {! go run(i, baton)! }! ! ! ! ! // start the race! baton <- 1! ! // wait for relay to finish! wg.Wait()! }
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) ! for i := 1; i < 5; i++ {! go run(i, baton)! }! ! ! ! ! // start the race! baton <- 1! ! // wait for relay to finish! wg.Wait()! } A channel that accepts an int
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) ! for i := 1; i < 5; i++ {! go run(i, baton)! }! ! ! ! ! // start the race! baton <- 1! ! // wait for relay to finish! wg.Wait()! } Go Routine
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) ! for i := 1; i < 5; i++ {! go run(i, baton)! }! ! ! ! ! // start the race! baton <- 1! ! // wait for relay to finish! wg.Wait()! } Writing to a channel
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) ! for i := 1; i < 5; i++ {! go run(i, baton)! }! ! ! ! ! // start the race! baton <- 1! ! // wait for relay to finish! wg.Wait()! } A WaitGroup - wait for 4 events!
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() }
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func run(leg int, baton chan int) { defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) ! ! ! // Massive CPU churn! ! ! for count := 0; count < 300; count++ {! ! ! ! for char := 0; char < 30000; char++ {! ! ! ! fmt.Printf("")! ! ! ! }! ! ! }! fmt.Printf("Leg %d.. churned, waiting to ! ! ! check_baton(leg, baton)! }
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func run(leg int, baton chan int) { defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) Done for WaitGroup ! ! ! // Massive CPU churn! ! ! for count := 0; count < 300; count++ {! ! ! ! for char := 0; char < 30000; char++ {! ! ! ! fmt.Printf("")! ! ! ! }! ! ! }! fmt.Printf("Leg %d.. churned, waiting to ! ! ! check_baton(leg, baton)! }
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() }
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func check_baton(leg int, baton chan int) {! ! ! for value := range baton {! ! ! ! switch value {! ! ! ! ! case leg:! ! ! ! ! ! // pass the baton! ! ! ! ! ! fmt.Println("Finished leg ", leg)! ! ! ! ! ! if leg == 4 {! ! ! ! ! ! ! close(baton)! ! ! ! ! ! } else {! ! ! ! ! ! ! ! baton <- leg + 1! ! ! ! ! ! }! ! ! ! ! ! return! ! ! ! ! default:! ! ! ! ! ! // ignore! ! ! ! ! ! baton <- value! ! ! ! }! ! ! }! }
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func check_baton(leg int, baton chan int) {! ! ! for value := range baton {! ! ! ! switch value {! ! ! ! ! case leg:Read ! or block on a ! ! ! ! ! // pass the channel baton! ! ! ! ! ! fmt.Println("Finished leg ", leg)! ! ! ! ! ! if leg == 4 {! ! ! ! ! ! ! close(baton)! ! ! ! ! ! } else {! ! ! ! ! ! ! ! baton <- leg + 1! ! ! ! ! ! }! ! ! ! ! ! return! ! ! ! ! default:! ! ! ! ! ! // ignore! ! ! ! ! ! baton <- value! ! ! ! }! ! ! }! }
Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func check_baton(leg int, baton chan int) {! ! ! for value := range baton {! ! ! ! switch value {! ! ! ! ! case leg:! ! ! ! ! ! // pass the baton! ! ! ! ! ! fmt.Println("Finished leg ", leg)! ! ! ! ! ! if leg == 4 {! ! ! ! ! ! ! close(baton)! ! ! ! ! ! } else {! ! ! ! ! ! ! ! baton <- leg + 1! ! ! ! ! ! }! ! ! ! ! ! return! ! ! ! ! default:! ! ! ! ! ! // ignore! ! ! ! ! ! baton <- value! ! ! ! }! ! ! }! }
The Big Fight https://flic.kr/p/9AeqD2
Generics? Convenient Too early still. interface{} https://flic.kr/p/9AeqD2
Keywords! Nah.. no rules, https://flic.kr/p/9AeqD2 rules! You need’em bro
GIL https://flic.kr/p/9AeqD2  Compiled language FTW
Extending & Embedding https://flic.kr/p/9AeqD2 Yeah Nope. ! Only Cgo
Tooling https://flic.kr/p/9AeqD2 gem bundler go tools
Emergency Instructions ! OR ! Lecture In Aerodynamics
Emergency Instructions
Emergency Instructions
Traction Control! Fuel Efficiency! Aerodynamics! Tyre Temperature
Traction Control! Fuel Efficiency! Aerodynamics! Tyre Temperature
“ Ruby is for developers Go is for programmers ” @gautamrege @joshsoftware

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RubyConf Portugal 2014 - Why ruby must go!

  • 4. Why Ruby Must Go! What can Ruby incorporate from Go? What is Programmer Awareness? As a Rubyist, what does Go teach me?
  • 6. Programming Paradigms Imperative Declarative Procedural Functional Object Oriented Symbolic
  • 7. Programming Paradigms Imperative Declarative Procedural Functional Object Oriented Symbolic C++! Java! Python! Ruby Order of execution / steps One or more subroutines
  • 8. Programming Paradigms Imperative Declarative Procedural Order of execution / steps One or more subroutines Functional Object Oriented Symbolic Pascal! FORTRAN! C
  • 9. Programming Paradigms Imperative Declarative Procedural Order of execution / steps One or more subroutines Functional Object Oriented Symbolic Pascal! FORTRAN! C! Go
  • 10. Go Lang C on Steroids
  • 11. Go Lang C on Steroids
  • 12. Go Lang C on Steroids • No more memory leaks. (Garbage collection)
  • 13. Go Lang C on Steroids • No more memory leaks. (Garbage collection) • No more pointer de-referencing. (-> or . )
  • 14. Go Lang C on Steroids • No more memory leaks. (Garbage collection) • No more pointer de-referencing. (-> or . ) • Support for maps, slices and channels.
  • 15. Go Lang C on Steroids • No more memory leaks. (Garbage collection) • No more pointer de-referencing. (-> or . ) • Support for maps, slices and channels. • Support for closures.
  • 16. Go Lang C on Steroids • No more memory leaks. (Garbage collection) • No more pointer de-referencing. (-> or . ) • Support for maps, slices and channels. • Support for closures. • Concurrency: closures, channels & go-routines.
  • 19. Go is different ! • No exceptions, only errors.
  • 20. Go is different ! • No exceptions, only errors. • Return multiple values from functions
  • 21. Go is different ! • No exceptions, only errors. • Return multiple values from functions • Interfaces but no classes (only structs)
  • 22. Go is different ! • No exceptions, only errors. • Return multiple values from functions • Interfaces but no classes (only structs) • No inheritance but embedded structs
  • 23. Let’s get Going And learn Go along the way!
  • 25. Duck Typing in Ruby Programming convenience.! Implicit Type Conversions.! No complex Type Inference
  • 26. Duck Typing in Ruby Programming convenience.! Implicit Type Conversions.! No complex Type Inference Don’t fight the Type System
  • 27. Duck Typing in Ruby Programming convenience.! Implicit Type Conversions.! No complex Type Inference Don’t fight the Type System Code First - Resolve Issues Later
  • 29. Problems with Duck Typing No Early Warning System! Reactive programming! Compiler Time checks!
  • 30. Problems with Duck Typing No Early Warning System! Reactive programming! Compiler Time checks! Type Inference
  • 31. Problems with Duck Typing No Early Warning System! Reactive programming! Compiler Time checks! Type Inference Code Once Correctly
  • 32. Types? Who cares? We’re ! Rubyists!
  • 33. Types? Who cares? We’re ! Rubyists!
  • 34. Type Checks in Ruby! def convert_hashes_to_parameters(key, value, assign_if_converted=true)! converted = convert_value_to_parameters(value)! #...! end! ! def convert_value_to_parameters(value)! if value.is_a?(Array) && !converted_arrays.member?(value)! #...! converted_arrays << converted! converted! elsif value.is_a?(Parameters) || !value.is_a?(Hash)! #...! end! end
  • 35. Type Checks in Ruby! def convert_hashes_to_parameters(key, value, assign_if_converted=true)! converted = convert_value_to_parameters(value)! #...! end! ! def convert_value_to_parameters(value)! if value.is_a?(Array) && !converted_arrays.member?(value)! #...! converted_arrays << converted! converted! elsif value.is_a?(Parameters) || !value.is_a?(Hash)! #...! end! end
  • 36. Type Checks in Ruby! def convert_hashes_to_parameters(key, value, assign_if_converted=true)! converted = convert_value_to_parameters(value)! #...! end! ! def convert_value_to_parameters(value)! if value.is_a?(Array) && !converted_arrays.member?(value)! #...! converted_arrays << converted! converted! elsif value.is_a?(Parameters) || !value.is_a?(Hash)! #...! end! end def permit!! each_pair do |key, value|! value = convert_hashes_to_parameters(key, value)! #...! end
  • 37. Type Checks in Ruby! def convert_hashes_to_parameters(key, value, assign_if_converted=true)! converted = convert_value_to_parameters(value)! #...! end! ! def convert_value_to_parameters(value)! if value.is_a?(Array) && !converted_arrays.member?(value)! #...! converted_arrays << converted! converted! elsif value.is_a?(Parameters) || !value.is_a?(Hash)! #...! end! end def permit!! each_pair do |key, value|! value = convert_hashes_to_parameters(key, value)! #...! end Strong Parameters!
  • 38. To Duck or to Type
  • 39. To Duck or to Type Best of Both worlds
  • 40. To Duck or to Type Light weight 1-level Type check
  • 41. To Duck or to Type Light weight 1-level Type check type point int ! func main() { var i int = 2 var j point = 2 ! i == j }
  • 42. To Duck or to Type Light weight 1-level Type check type point int ! func main() { var i int = 2 var j point = 2 Variable name first, then the type ! i == j }
  • 43. To Duck or to Type Light weight 1-level Type check type point int ! func main() { var i int = 2 var j point = 2 ! i == j }
  • 44. To Duck or to Type Light weight 1-level Type check type point int ! func main() { var i int = 2 var j point = 2 ! i == j } Error: invalid operation: i == j (mismatched types int and point)
  • 45. Ruby re-defines Object Oriented Concepts, Go re-defines programming itself! “ ”
  • 49. Programmer Awareness %QORKNGT 4GXKGYGT (TCOGYQTM
  • 50. Programmer Awareness %QORKNGT 4GXKGYGT (TCOGYQTM .CPIWCIG
  • 51. Programmer Awareness Variable declaration and assignment
  • 52. Programmer Awareness Variable declaration and assignment y y
  • 53. Programmer Awareness Variable declaration and assignment y := 2 // y is of type int! y = "3" Implicit declaration
  • 54. Programmer Awareness Variable declaration and assignment y := 2 // y is of type int! y = "3" Assignment
  • 55. Programmer Awareness Variable declaration and assignment y := 2 // y is of type int! y = "3" COMPLIER ERROR! cannot use “3” (type string) as type int in assignment
  • 56. Programmer ERROR? Variable declaration and assignment y := 2 // y is of type int! y = "3" As a programmer, we probably re-assigned “y” to a String by mistake!
  • 57. Programmer AWARENESS Variable declaration and assignment y := 2 // y is of type int! y, _ = strconv.Atoi("3") There’s always a right way to do things!
  • 59. ! Eh… what? https://flic.kr/p/mnZgQw
  • 60. Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! }
  • 61. Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! } import packages
  • 62. Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! } Exported function
  • 63. Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! }
  • 64. Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! } I’m practical. You can re-declare err in your code!* * Conditions apply
  • 65. Programmer Awareness Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! d, err := f.Stat()! }
  • 66. Programmer Awareness Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! f, err := f.Stat()! }
  • 67. Programmer Awareness Variable Re-declaration import "os"! Error: no new ! variables on left func main() {! side of := ! f, err := os.Open("somefile")! ! // handle error! ! ! f, err := f.Stat()! } Hmm.. I think you re-used the variable f by mistake!
  • 68. Programmer Awareness Variable Re-declaration import "os"! ! func main() {! ! f, err := os.Open("somefile")! ! // handle error! ! ! f, err = f.Open("other file")! } Re-assign ! explicitly.. 
  • 69.
  • 70. With Great Power Comes Great Responsibility
  • 73. Lets Go a little more! type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Dimensions)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } Type Declaration
  • 74. Lets Go a little more! type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Dimensions)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } Exported Array
  • 75. Lets Go a little more! type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Dimensions)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } Exported Array The size in Array is part of the type! [2]float32 != [3]float32
  • 76. Lets Go a little more! type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Dimensions)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } Embedding! (Not inheritance)
  • 77. Lets Go a little more! type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Dimensions)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } hotel.Dimensions and not hotel.Hall.Dimensions
  • 78. Lets Go a little more! func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } Dimensions)!
  • 79. Lets Go a little more! func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! }
  • 80. Programmer Awareness type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! }
  • 81. Programmer Awareness type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! } Which Name should I use? Error: Ambiguous selector hotel.Name!
  • 82. Programmer Awareness type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Name)Hall.! Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! }
  • 83. Programmer Awareness type Layout struct {! ! Name string! Capacity int! }! ! type Hall struct {! ! Name string! ! Dimensions [2]float32! }! ! type Hotel struct {! ! Location string! ! Hall! ! Layout! } func main() {! ! hotel := Hotel{}! ! fmt.Println(hotel.Hall.Name)! ! ! h := make(map[string]Hotel)! ! ! for name, _ := range h {! ! ! fmt.Println(name)! ! }! }
  • 84. Modules in Ruby module Layout! def manager! p "Layout Manager"! end! end! ! module Hall! def manager! p "Hall Manager"! end! end! ! class Hotel! include Layout! include Hall! end def main! hotel = Hotel.new! p hotel.manager! end
  • 85. Modules in Ruby module Layout! def manager! p "Layout Manager"! end! end! ! module Hall! def manager! p "Hall Manager"! end! end! ! class Hotel! include Layout! include Hall! end def main! hotel = Hotel.new! p hotel.manager! end Which language is this dude?
  • 86. Include modules in order! https://flic.kr/p/e7SnAa
  • 87. Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! }
  • 88. Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! } Map of strings and Hotels
  • 89. Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! } Easy iteration syntax!
  • 90. Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! } Blank Identifier - ignore value
  • 91. Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! }
  • 92. Programmer Awareness Iterating a Hash hotels := make(map[string]Hotel)! ! for name, _ := range hotels {! ! fmt.Println(name)! } Bad practice! ! I’ll randomise the order!
  • 95. Pushing some Goodies into Ruby https://flic.kr/p/awu6ZA
  • 96. Defer mu sync.Mutex! ! func foo() {! mu.Lock()! defer mu.unLock()! // do something...! } https://flic.kr/p/awu6ZA
  • 97. Defer func trace(s string) { fmt.Println("entering:", s) }! func untrace(s string) { fmt.Println("leaving:", s) }! ! func a() {! trace("a")! defer untrace("a")! // do something....! } https://flic.kr/p/awu6ZA
  • 98. Concurrency Parallelism Multi-core Processing https://flic.kr/p/awu6ZA
  • 99. Example - Relay Race • 4 legs of the race • Each leg does processing concurrently. • Completion should be in order. (pass the baton)
  • 100. Concurrent Example Leg 1 Leg 2 Leg 3 Leg 4
  • 101. Concurrent Processing Leg 1 Leg 2 Leg 3 Leg 4 CPU churn - CPU time consuming operation.
  • 102. Completion Order Leg 1 Leg 2 Leg 3 Leg 4
  • 103. Completion Order Leg 1 Leg 2 Leg 3 Leg 4
  • 104. Completion Order Leg 1 Leg 2 Leg 3 Leg 4
  • 105. Completion Order Leg 1 Leg 2 Leg 3 Leg 4
  • 106.
  • 107.
  • 108. CSP! Communicating Sequential Processes https://flic.kr/p/6MwYFo https://flic.kr/p/awu6ZA
  • 109. CSP! Communicating Sequential Processes since 1978 !! https://flic.kr/p/awu6ZA https://flic.kr/p/6MwYFo
  • 110. package main ! import ( "fmt" "runtime" "sync" ) ! var wg sync.WaitGroup ! /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1
  • 111. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() }
  • 112. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) ! for i := 1; i < 5; i++ {! go run(i, baton)! }! ! ! ! ! // start the race! baton <- 1! ! // wait for relay to finish! wg.Wait()! }
  • 113. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) ! for i := 1; i < 5; i++ {! go run(i, baton)! }! ! ! ! ! // start the race! baton <- 1! ! // wait for relay to finish! wg.Wait()! } A channel that accepts an int
  • 114. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) ! for i := 1; i < 5; i++ {! go run(i, baton)! }! ! ! ! ! // start the race! baton <- 1! ! // wait for relay to finish! wg.Wait()! } Go Routine
  • 115. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) ! for i := 1; i < 5; i++ {! go run(i, baton)! }! ! ! ! ! // start the race! baton <- 1! ! // wait for relay to finish! wg.Wait()! } Writing to a channel
  • 116. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) ! for i := 1; i < 5; i++ {! go run(i, baton)! }! ! ! ! ! // start the race! baton <- 1! ! // wait for relay to finish! wg.Wait()! } A WaitGroup - wait for 4 events!
  • 117. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() }
  • 118. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func run(leg int, baton chan int) { defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) ! ! ! // Massive CPU churn! ! ! for count := 0; count < 300; count++ {! ! ! ! for char := 0; char < 30000; char++ {! ! ! ! fmt.Printf("")! ! ! ! }! ! ! }! fmt.Printf("Leg %d.. churned, waiting to ! ! ! check_baton(leg, baton)! }
  • 119. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func run(leg int, baton chan int) { defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) Done for WaitGroup ! ! ! // Massive CPU churn! ! ! for count := 0; count < 300; count++ {! ! ! ! for char := 0; char < 30000; char++ {! ! ! ! fmt.Printf("")! ! ! ! }! ! ! }! fmt.Printf("Leg %d.. churned, waiting to ! ! ! check_baton(leg, baton)! }
  • 120. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() }
  • 121. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func check_baton(leg int, baton chan int) {! ! ! for value := range baton {! ! ! ! switch value {! ! ! ! ! case leg:! ! ! ! ! ! // pass the baton! ! ! ! ! ! fmt.Println("Finished leg ", leg)! ! ! ! ! ! if leg == 4 {! ! ! ! ! ! ! close(baton)! ! ! ! ! ! } else {! ! ! ! ! ! ! ! baton <- leg + 1! ! ! ! ! ! }! ! ! ! ! ! return! ! ! ! ! default:! ! ! ! ! ! // ignore! ! ! ! ! ! baton <- value! ! ! ! }! ! ! }! }
  • 122. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func check_baton(leg int, baton chan int) {! ! ! for value := range baton {! ! ! ! switch value {! ! ! ! ! case leg:Read ! or block on a ! ! ! ! ! // pass the channel baton! ! ! ! ! ! fmt.Println("Finished leg ", leg)! ! ! ! ! ! if leg == 4 {! ! ! ! ! ! ! close(baton)! ! ! ! ! ! } else {! ! ! ! ! ! ! ! baton <- leg + 1! ! ! ! ! ! }! ! ! ! ! ! return! ! ! ! ! default:! ! ! ! ! ! // ignore! ! ! ! ! ! baton <- value! ! ! ! }! ! ! }! }
  • 123. Channels in action p!ackage main import ( "fmt" "runtime" "sync" )! v!ar wg sync.WaitGroup /* * Each go-routine sleeps at random(1-5) seconds. * This is simulating long working process * Then we finish in order */ func check_baton(leg int, baton chan int) { for value := range baton { switch value { case leg: // pass the baton fmt.Println("Finished leg ", leg) if leg == 4 { close(baton) } else { baton <- leg + 1 } return default: // ignore baton <- value } } }! func run(leg int, baton chan int) { ! defer wg.Done() fmt.Printf("Leg %d.. churningn", leg) // Massive CPU churn for count := 0; count < 300; count++ { for char := 0; char < 30000; char++ { fmt.Printf("") } ! } fmt.Printf("Leg %d.. churned, waiting to exitn", leg) ! check_baton(leg, baton) }! func main() { runtime.GOMAXPROCS(4) ! baton := make(chan int) wg.Add(4) for i := 1; i < 5; i++ { ! go run(i, baton) } ! // start the race baton <- 1 // wait for relay to finish wg.Wait() } func check_baton(leg int, baton chan int) {! ! ! for value := range baton {! ! ! ! switch value {! ! ! ! ! case leg:! ! ! ! ! ! // pass the baton! ! ! ! ! ! fmt.Println("Finished leg ", leg)! ! ! ! ! ! if leg == 4 {! ! ! ! ! ! ! close(baton)! ! ! ! ! ! } else {! ! ! ! ! ! ! ! baton <- leg + 1! ! ! ! ! ! }! ! ! ! ! ! return! ! ! ! ! default:! ! ! ! ! ! // ignore! ! ! ! ! ! baton <- value! ! ! ! }! ! ! }! }
  • 124. The Big Fight https://flic.kr/p/9AeqD2
  • 125. Generics? Convenient Too early still. interface{} https://flic.kr/p/9AeqD2
  • 126. Keywords! Nah.. no rules, https://flic.kr/p/9AeqD2 rules! You need’em bro
  • 127. GIL https://flic.kr/p/9AeqD2  Compiled language FTW
  • 128. Extending & Embedding https://flic.kr/p/9AeqD2 Yeah Nope. ! Only Cgo
  • 130.
  • 131. Emergency Instructions ! OR ! Lecture In Aerodynamics
  • 134.
  • 135. Traction Control! Fuel Efficiency! Aerodynamics! Tyre Temperature
  • 136. Traction Control! Fuel Efficiency! Aerodynamics! Tyre Temperature
  • 137. “ Ruby is for developers Go is for programmers ” @gautamrege @joshsoftware