fmt.Printf(“Hello, UNSADA”)

Pramesti Hatta K.

Software Engineer @Tech in Asia

Making things look hard is easy. Making hard things look easy, that’s hard.

Meet Gopher, the funniest programming language mascot.

2 types of programming language

compiled | interpreted

compiled languages are converted directly into machine code

In contrast to compiled languages, interpreted languages do not require machine

code in order to execute the program; instead, interpreters will run through a program line by line and execute each

command.

compiled

● often faster execution time

● often slower development time

C/C++, Go, Fortran, Pascal etc

interpreted

● often slower execution time

● often faster development time

PHP, Python, Ruby, JavaScript

statically typed

package main

import “fmt”

func main() { var person string

person = “Maudy Ayunda” fmt.Println(person) person = 22 fmt.Println(person)}

Output:cannot use 22 (type int) as type string in assignment

dynamically typed

<?php$person = “Maudy Ayunda”;echo $person;

$person = 22;Echo $person;

Output:Maudy Ayunda22

New programming language?

2007

Robert Griesemer, Rob Pike and Ken Thompson

2009 (became open source)

2012 (finally stable v.)

why?

Go was born out of frustration with existing languages and environments for systems

programming.

one had to choose either efficient compilation, efficient execution, or ease of

programming

programmers who could were choosing ease over safety and efficiency by moving to

dynamically typed languages such as Python and JavaScript rather than C++ or, to a

lesser extent, Java.

Go is an attempt to combine the ease of programming of an interpreted, dynamically

typed language with the efficiency and safety of a statically typed, compiled language.

designed by Google to solve Google’s problem.

and Google has big problems.

Big hardware

Big software

● C++ (mostly) for servers, plus lots of java and python

● thousands of engineers● gazillions of lines of code

development at Google can be slow, often clumsy.

Goals

● eliminate slowness● eliminate clumsiness● improve effectiveness

Go’s purpose is not research into programming language design

Go’s purpose is to make software engineer’s lives better.

Go Programming Language

● open source● concurrent● garbage collected● efficient● simple● fun● boring (to some)

https://golang.org

Go is a statically typed compiled language.

Golang is a simple language. It has only 25 keywords.

Go keywordsbreak default func interface selectcase defer go map structchan else goto package switchconst fallthrough if range typecontinue for import return var

Yea I’m ready to learn this language

Basic structure1.package main

2.

3.import “fmt”

4.

5.func main() {

6. fmt.Printf(“Hello, world.\n”)

7.}

Package1.package main

2.

3.import (

4. “fmt”

5. “math/rand”

6.)

7.

8.func main() {

9. fmt.Println("My favorite number is", rand.Intn(10))

10.}

Function1.package main

2. …

3.func add(x int, y int) int {

4. return x + y

5.}

6.

7.func main() {

8. fmt.Println(add(22, 8))

9.}

Output30

Function with multiple return1.package main

2. …

3.func swap(x, y string) (string, string) {

4. return y, x

5.}

6.

7.func main() {

8. a, b := swap(“hello”, “world”)

9. fmt.Println(a, b))

10.}

Outputworld hello

Variables1.package main

2. …

3.var x int

4.

5.func main() {

6. var y string

7. y = "Hi!"

8. fmt.Println(y)

9. fmt.Println(x)

10.}

OutputHi!0

Short declaration variables1.package main

2. …

3.

4.func main() {

5. y := “Hi!”

6. fmt.Println(y)

7.}

OutputHi!

Basic typesbool

string

int int8 int16 int32 int64

uint uint8 uint16 uint32 uint64 uintptr

byte // alias for uint8

rune // alias for int32

float32 float64

complex64 complex128

Looping1.package main

2. …

3.

4.func main() {

5. for i := 1; i <= 10; i++ {

6. fmt.Println(i)

7. }

8.}

Output12345678910

Looping continued1.package main

2. …

3.

4.func main() {

5. i := 1

6. for i <= 10 {

7. fmt.Println(i)

8. i++

9. }

10.}

Output12345678910

If and else1.package main

2. …

3.

4.func main() {

5. i := 22

6. if i > 10 {

7. fmt.Println(“big”)

8. } else {

9. fmt.Println(“low”)

10. }

11.}

Outputbig

Struct1.package main

2. …

3.

4.type PersegiPanjang struct {

5. P, L int

6.}

7.func main() {

8. fmt.Println(PersegiPanjang{P: 10, L: 22})

9.}

Output{10 22}

Array, slice, map, methods, pointer, interfaces etc.

https://tour.golang.org/list

What the heck is concurrency

concurrency

concurrenc

y

concurrenc

y

concurrenc

y concurre

nc

y

concurrenc

y

concurrencyconcurrency

concurrenc

y

concurrenc

y

concurrencyconcurrenc

y

concurrenc

y concurrenc

y

concurrenc

y

concurrency con

curren

c

y

concurrency

People will tend to say ...

concurrency is doing two or more things simultaneously,

parallelism is doing two or more things simultaneously.

concurrency is not parallelism

concurrency

“Gue lagi ngobrol sambil ngopi”

parallelism

“Gue lagi ngoding sambil denger musik”

concurrency is the composition of independently executing processes

parallelism is the simultaneous execution of (possibly related)

computations

concurrency is about dealing with lots of things at once. parallelism is about doing lots of things at

once

concurrency is about the structure. while parallelism is about the

execution.

but, concurrency can enable parallelism

how?

to have true parallelism you need to run your program on a machine with

multiple physical processors

You need analogies

Imagine you have a restaurant

you have no employee

You only have one stove

there is one customer

she orders “omelette” and “french fries”

Without concurrency

1.you go to the kitchen

2.you make omelette

3.when omelette is done, give it to the customer

4.you go back to the kitchen

5.you make french fries

6.when french fries is done, give it to the customer

With concurrency

1.you go to the kitchen

2.you ask your employee to cook french fries

3.you make omelette OR your employee make french fries

4.when omelette/french fries is done, give it to the customer

NOTE: THIS TIME YOU HAVE ONE EMPLOYEE BUT YOU ONLY HAVE ONE STOVE

With concurrency + parallelism

1.you go to the kitchen

2.you ask your employee to cook french fries

3.you make omelette AND your employee make french fries

4.when omelette/french fries is done, give it to the customer

NOTE: THIS TIME YOU HAVE ONE EMPLOYEE AND YOU HAVE TWO STOVES

1 2 3 4 5 6 7 8 9 10

DOCTOR

IN (4 MINUTES)

CHECK-UP (5 MINUTES)

TIME REQUIRED FOR 1 PERSON4 + 5 = 9 MINUTES

TIME REQUIRED FOR ALL PERSON9 * 10 = 90 MINUTES

WITHOUT CONCURRENCY

1 2 3 4 5 6 7 8 9 10

DOCTOR

IN (4 MINUTES)

CHECK-UP (5 MINUTES)

TIME REQUIRED FOR 5 PERSON4 + 5 * 5 = 29 MINUTES

TIME REQUIRED FOR ALL PERSON29 * 2 = 58 MINUTES

WITH CONCURRENCY

1 2 3 4 5 6 7 8 9 10

DOCTOR

IN (4 M

INUTES)

CHECK-UP (5 MINUTES)

TIME REQUIRED FOR ALL PERSON4 + 5 * 5 = 29 MINUTES

WITH CONCURRENCY + PARALLELISM

DOCTOR

CHECK-UP (5 MINUTES)

IN (4 MINUTES)

Companies currently using Go throughout the world

https://github.com/golang/go/wiki/GoUsers

Where to goTour of Go (https://tour.golang.org)

Go by Example (https://gobyexample.com/)

An Introduction to Programming in Go (https://www.golang-book.com/books/intro)

Google it.

Thank you!