So  you want to be a Gopher

Hackference, 2016

James Milner

Software Engineer

@JamesLMilner

james@loxodrome.io

Why this talk?

What is Go?

Go is a compiled, statically typed programming language created at Google in 2007 by by Robert Griesemer, Rob Pike, and Ken Thompson

How did I get here?

Humble Beginnings 

# Python

x = 10
x = "Hello World"
x = 1.1

print x

# JavaScript

var x = 10;
x = "Hello World";
x = 1.1;

console.log(x)

function dis() { return this }
// undefined

five = dis.call(5)
// [Number: 4]

five.wtf = 'potato'
// 'potato'

five.wtf
// 'potato'

five * 5 
# 25

five.wtf
// 'potato'

five++ 
// 5

five.wtf
// undefined

You can take this a step further

The Javas

public class HelloWorld {

    public static void main(String[] args) {
        // Prints "Hello, World" to the terminal window.
        String hello = new String("Hello World");
        System.out.println(hello);
    }

}

"The problem is you can be productive, or you can be safe, but you can't really be both" - Rob Pike, 2009

Reasons I like Go

• Typed language
• Fast
• Comprehensive standard library
• Clean syntax
• Memory managed
• API doesn't change much
• UTF-8 by default

'That's super great James, but just give me the low down'

The Different Parts

Assignments

// JAVASCRIPT (ES5)

var a = "Hello";
var b; // b === undefined

// GO LANG

var string a = "Hello"
var b = "Hello"
c := "Hello"

var d string // Defaults to empty string

if/else

// JAVASCRIPT

if (someCondition) {

    doSomething()

} 
else {

    doSomethingElse()    

}

For Loops

for {

    doSomethingEndlessly()

}

for x < 10 {

    x++

}

for i := 0; i <= 9; i++ {

    fmt.Println(i)

}

for i, num := range nums {
    if num == 3 {
        fmt.Println("index:", i)
    }
}

arrays

slices!

• We do have arrays in Go

• We use them far less frequently than slices

• Arrays in Go have a fixed length

• Slices can be of varying length

Errors

Errors are just values in Go

func f1(arg int) (int, error) {

    if arg == 42 {

        return -1, errors.New("can't work with 42")
    }

    return arg + 5, nil

}

Pointers

Errors are just values in Go

package main
	
import "fmt"

func zeroval(ival int) {
    ival = 0
}

func zeroptr(iptr *int) {
    *iptr = 0
}

func main() {
    i := 1
    fmt.Println("initial:", i)

    zeroval(i)
    fmt.Println("zeroval:", i)

    zeroptr(&i) //The &i syntax gives the memory address
    fmt.Println("zeroptr:", i)
}

The Cool Parts

Multi Returns

// PYTHON 2

def vals:
    return [3, 7]


// GO LANG

func vals() (int, int) {
    return 3, 7
}

Variadic Functions

func sum(nums ...int) {
    fmt.Print(nums, " ")
    total := 0
    for _, num := range nums {
        total += num
    }
    fmt.Println(total)
}

Structs

    
    type Person struct {
        name string
        job string
        age int
        phrase string
    }
    
    hugh := Person{
        name: "Hugh",
        job : "The Spotifys",
        age : 23,
        phrase : "That sound's sub optimal",
    }

    fmt.Println(hugh.phrase)

Go Routines / Channels

The Tools