The document is a presentation about getting started with the Go programming language. It covers Abiola Ibrahim's experience with Go, introduces core Go concepts like types, functions, concurrency, and building a sample attendance tracking application. It also discusses using Go on Google App Engine and examples of companies adopting Go in production.

1. 13
December
2014
getting started with
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
Go
Programming
Language
Abiola
Ibrahim
@abiosoB

2. 13
December
2014
AGENDA
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• My
Go
Story
• IntroducGon
to
Go
• Build
our
applicaGon
• Go
on
App
Engine
• AdopGon
of
Go
• Useful
Links

3. 13
December
2014
My
Go
Story
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• Interpreted
Languages
have
slower
runGmes
and
no
compile
Gme
error
checks.
• I
like
Java
but
not
the
JVM
overhead.
• Building
C++
is
not
as
fun
as
desired.
• Go
is
compiled,
single
binary
(no
dependencies)
and
builds
very
fast.

4. Real
World
Go
talk
-­‐
Andrew
Gerrand,
2011.
13
December
2014
Why
Go
?
“
“Speed,
reliability,
or
simplicity:
pick
two.”
(some9mes
just
one).
Can’t
we
do
be@er?
”
Ge.ng
Started
with
Go
|
Abiola
Ibrahim

5. 13
December
2014
Scope
of
Talk
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• Things
this
talk
cannot
help
you
do
– Build
Drones
– Create
Google.com
killer
– Replicate
Facebook
• Things
this
talk
can
help
you
do
– Understand
the
core
of
Go
– Start
wriGng
Go
apps

6. INTRODUCTION
TO
GO
13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim

7. Go
is
staGcally
typed,
but
type
inference
saves
repeGGon.
13
December
2014
Simple
Type
System
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
Java/C/C++:
int i = 1;
Go:
i := 1 // type int
pi := 3.142 // type float64
hello := "Hello, GDays!" // type string
add := func(x, y int) int { return x + y }
//type func (x, y int)

8. Statements
are
terminated
with
semicolons
but
you
don’t
need
to
include
it.
var a int = 1 // valid line
var b string = “GDays”; // also valid line
13
December
2014
Syntax
and
Structure
Ge.ng
Started
with
Go
|
Abiola
Ibrahim

9. iota
can
come
handy
in
constants
const EVENT = “GDays” //value cannot change
const (
ANDROID_SESSION = iota // 0
GOLANG_SESSION // 1
GIT_SESSION // 2
13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
)

10. 13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
No
brackets,
just
braces.
if a < 0 {
fmt.Printf(“%d is negative”, a)
}
for i := 0; i< 10; i++ {
fmt.Println(“GDays is awesome”)
}

11. No
while,
no
do
while,
just
for.
for i < 10 { ... } //while loop in other languages
for { ... } //infinite loop
// range over arrays, slices and maps
nums := [4]int{0, 1, 2, 3}
for i, value := range nums {
fmt.Println(“value at %d is %d”, i, value)
}
gdays := map[string]string{ “loc” : “Chams City”, ... }
for key, value := range gdays {
fmt.Println(“value at %s is %s”, key, value)
13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
}

12. If
statement
supports
iniGalizaGon.
file, err := os.Open(“sample.txt”)
if err == nil {
fmt.Println(file.Name())
}
This
can
be
shortened
to
if file, err := os.Open(“sample.txt”); err == nil {
fmt.Println(file.Name())
13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
}

13. 13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
MulGple
return
values.
func Sqrt(float64 n) (float64, err) {
if (n < 0){
return 0, errors.New(“Negative number”)
}
return math.Sqrt(n), nil
}

14. 13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
MulGple
assignments.
a, b, c := 1, 2, 3
func Reverse(str string) string {
b := []byte(str)
for i, j := 0, len(b)-1; i != j; i, j = i+1, j-1 {
b[i], b[j] = b[j], b[i]
}
return string(b)
}

15. var nums [4]int //array declaration
nums := [4]int{0, 1, 2, 3} //declare and initialize
n := nums[0:2] // slice of nums from index 0 to 1
n := nums[:2] // same as above
n := nums[2:] // from index 2 to max index
n := nums[:] // slice of entire array
nums[0] = 1 // assignment
n[0] = 2 // assignment
var copyOfNum = make([]int, 4) //slice allocation
copy(copyOfNum, nums[:]) //copy nums into it
13
December
2014
Arrays
and
Slices
Ge.ng
Started
with
Go
|
Abiola
Ibrahim

16. var gdays map[string]string //declaration
gdays = make(map[string]string) //allocation
//shorter declaration with allocation
var gdays = make(map[string]string)
gdays := make(map[string]string)
gdays[“location”] = “Chams City” //assignment
//declaration with values
gdays := map[string]string {
“location” : “Chams City”
13
December
2014
Maps
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
}

17. 13
December
2014
Structs
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
type Point struct {
X int,
Y int,
Z int,
}
var p = &Point{0, 1, 3}
//partial initialization
var p = &Point{
X: 1,
Z: 2,
}

18. //void function without return value
func SayHelloToMe(name string){
fmt.Printf(”Hello, %s”, name)
}
//function with return value
func Multiply(x, y int) int {
13
December
2014
FuncGons
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
return x * y
}

19. 13
December
2014
Methods
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
type Rectangle struct {
X, Y int
}
func (r Rectangle) Area() int {
return r.X * r.Y
}
r := Rectangle{4, 3} // type Rectangle
r.Area() // == 12

20. Types
and
Methods
You
can
define
methods
on
any
type.
type MyInt int
func (m MyInt) Square() int {
i := int(m)
return i * i
}
num := MyInt(4)
num.Square() // == 16
13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim

21. 13
December
2014
Scoping
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• Package
level
scope
• No
classes
• A
package
can
have
mulGple
source
files
• Package
source
files
reside
in
same
directory
package main // sample package declaration

22. 13
December
2014
Visibility
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• No
use
of
private
or
public
keywords.
• Visibility
is
defined
by
case
//visible to other packages
var Name string = “”
func Hello(name string) string {
return fmt.Printf(“Hello %s”, name)
}
//not visible to other packages
var name string = “”
func hello(name string) string {
return fmt.Printf(“Hello %s”, name)
}

23. 13
December
2014
Concurrency
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• GorouGnes
are
like
threads
but
cheaper.
MulGple
per
threads.
• CommunicaGons
between
gorouGnes
are
done
with
channels
done := make(chan bool) //create channel
doSort := func(s []int) {
sort(s)
done <- true //inform channel goroutine is done
}i
:= pivot(s)
go doSort(s[:i])
go doSort(s[i:])
<-done //wait for message on channel
<-done //wait for message on channel

24. BUILDING
OUR
APPLICATION
13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim

25. Download
Go
installer
for
your
pladorm
at
hep://golang.org/doc/install
13
December
2014
InstallaGon
Ge.ng
Started
with
Go
|
Abiola
Ibrahim

26. 13
December
2014
Code
Session
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• Let
us
build
a
GDays
Aeendance
app.
• Displays
total
number
of
aeendees
• Ability
to
mark
yourself
as
present
Source
code
will
be
available
aBer
session
at
hep://github.com/abiosoB/gdays-­‐ae

27. GO
ON
APP
ENGINE
13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim

28. 13
December
2014
Code
Session
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• Let
us
modify
our
app
to
suit
App
Engine
– Use
User
service
to
uniquely
idenGfy
user
– Use
Data
Store
to
persist
number
of
aeendees
Source
code
will
be
available
aBer
session
at
hep://github.com/abiosoB/gdays-­‐ae-­‐appengine

29. ADOPTION
OF
GO
13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim

30. 13
December
2014
Go
in
ProducGon
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• Google
• Canonical
• DropBox
• SoundCloud
• Heroku
• Digital
Ocean
• Docker
And
many
more
at
hep://golang.org/wiki/GoUsers

31. 13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
USEFUL
LINKS

32. 13
December
2014
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• hep://golang.org/doc
-­‐
official
documentaGon
• hep://tour.golang.org
-­‐
interacGve
tutorials
• hep://gobyexample.com
-­‐
tutorials
• hep://gophercasts.io
-­‐
screencasts
• hep://golang.org/wiki/ArGcles
-­‐
lots
of
helpful
arGcles

33. 13
December
2014
Community
Ge.ng
Started
with
Go
|
Abiola
Ibrahim
• Blog
– hep://blog.golang.org
• Google
Group
– heps://groups.google.com/d/forum/golang-­‐nuts
• Gopher
Academy
– hep://gopheracademy.com
• Me
– hep://twieer.com/abiosoB
– abiola89@gmail.com

34. 13
December
2014
THANK
YOU
Ge.ng
Started
with
Go
|
Abiola
Ibrahim