An introduction to the go programming language, emphasizing concurrency.

1. Go
ahead,
make
my
day.
Intro
to
Go
programming
language

2. Me
@torkale
h8p://github.com/torkale
torkale[at]gmail

3. Why
Go?

4. Challenge
Safety
&
Performance
Expressiveness
&
Convenience

5. Mascot
Performance
Type
safety
Concurrency
Scalability
ProducKvity
AL

6. Respected
Parents
Ken
Thompson
Unix,
B,
UTF-­‐8,
Plan
9
Rob
Pike
Plan
9,
UTF-­‐8,
Limbo,
Unix
team
The
Unix
Programming
Environment
The
PracKce
of
Programming

7. History
Rob
Pike
Ken
Thompson
Robert
Griesmer
Start
Late
2007
Public
2009
Go
1.0
March
2012
Go
1.1
May
2013

9. Hello
package
main
import
"fmt"
func
greet()
{
fmt.Println("Hello,
I
love
you,
won’t
you
tell
me
your
name?”)
}
func
main()
{
greet()
}

10. Web
Server
package
main
import
(
"fmt"
"net/h8p"
)
func
handler(w
h8p.ResponseWriter,
r
*h8p.Request)
{
fmt.Fprine(w,
”Request
from
%s",
r.URL.Path[1:])
}
func
main()
{
h8p.HandleFunc("/",
handler)
h8p.ListenAndServe(":8080",
nil)
}

11. Basic
types
DeclaraKons
CondiKons
Loops
Slice
Map
BASICS

12. Basic
Types
bool
string
int
int8
int16
int32
int64
uint
uint8
uint16
uint32
uint64
uintptr
byte
//
alias
for
uint8
rune
//
alias
for
int32
//
represents
a
Unicode
code
point
float32
float64
complex64
complex128

13. DeclaraKons
var
i
int
i
=
getInteger()
j
:=
getInteger()
value,
err
:=
getValueOrError()
value2,
_
:=
getValueOrError()

14. CondiKons
var
even
bool
if
x%2
==
0
{
even
=
true
}
if
x%2
==
0
{
even
=
true
}
else
{
even
=
false
}
if
mod
:=
x%2;
mod
==
0
{
even
=
true
}

15. Loops
factorial
:=
1
for
i
:=
2;
i
<=
num;
i++
{
factorial
*=
i
}
nextPowerOf2
:=
1
for
nextPowerOf2
<
num
{
nextPowerOf2
*=2
}
for
{
//
Forever
}

16. Slice
primes
:=
[]int{2,
3,
5,
7,
11,
13}
fmt.Println("primes[1:4]
==",
primes[1:4])
zeroes
:=
make([]int,
5)
fmt.Println("zeroes
==",
zeroes)
for
i,
v
:=
range
primes
{
fmt.Prine("(%d)
=
%dn",
i,
v)
}
for
_,
v
:=
range
primes
{
fmt.Prine("%dn",
v)
}

17. Map
m
:=
make(map[string]int)
m["Ten"]
=
10
fmt.Println(m)
capitals
:=
map[string]string{
"Jerusalem":
"Israel",
"Paris":
"France",
"London":
"UK",
}
fmt.Println(capitals)
delete(capitals,
"London")
v,
present
:=
capitals["London"]
fmt.Println("The
capital:",
v,
"Present?",
present)

18. Custom
types
Extension
via
composiKon
Methods
TYPES

19. Custom
Types
type
Name
string
type
Person
struct
{
first
Name
last
Name
}
type
Hero
struct
{
Person
power
string
}
type
Crowd
struct
{
people
[]Person
}

20. Methods
func
(dude
Person)
FullName()
string
{
return
fmt.Sprine("%s
%s",
dude.first,
dude.last)
}
func
(dude
Person)
SetFirst(name
Name)
{
dude.first
=
name
}
func
(h
*Hero)
ToString()
string
{
return
fmt.Sprine("Name:
%s
Power:
%s",
h.FullName(),
h.power)
}
func
NewPerson(f,
l
Name)
Person
{
return
Person{f,
l}
}

21. AbstracKon
Duck
typing
Signatures
Implicit
INTERFACES

22. interfaces
type
Talker
interface
{
Talk()
string
}
func
(dude
Person)
Talk()
string
{
return
fmt.Sprine("My
name
is
%s",
dude.FullName())
}
func
MakeSomeoneTalk(talker
Talker)
string
{
return
talker.Talk()
}
func
interfaces()
{
fmt.Println(MakeSomeoneTalk(NewPerson("Robert",
"de
Niro")))
}

23. Higher-­‐order
funcKons
Custom
funcKon
types
Closures
MulKple
return
values
FUNCTIONS

24. FuncKons
type
PersonAcKon
func(some
Person)
Name
func
(crowd
Crowd)
ConcatPersonAcKons(acKon
PersonAcKon)
string
{
var
result
string
for
_,
dude
:=
range
crowd.people
{
result
=
fmt.Sprine("%s
%s",
result,
acKon(dude))
}
return
result
}
func
AllLastNames(crowd
Crowd)
string
{
return
crowd.ConcatPersonAcKons(func(dude
Person)
Name
{
return
dude.last
})
}

25. defer
func
MeasureStart(label
string)
(string,
Kme.Time)
{
return
label,
Kme.Now()
}
func
Measure(label
string,
startTime
Kme.Time)
{
duraKon
:=
Kme.Now().Sub(startTime)
fmt.Println(label,
"ComputaKon
took",
duraKon)
}
func
benchmark()
{
defer
Measure(MeasureStart("benchmark()"))
Kme.Sleep(Kme.Second)
}

26. CSP
go-­‐rouKne
channels
select
CONCURRENCY

27. CommunicaKng
SequenKal
Processes
“Do
not
communicate
by
sharing
memory;
instead
share
memory
by
communicaKng”

28. go
rouKnes
var
a
string
func
Init()
{
a
=
"finally
started"
return
}
func
doSomethingElse()
{
//
…
}
func
Simple()
string{
go
Init()
doSomethingElse()
return
a
}

29. tradiKonal
var
(
a
string
wg
sync.WaitGroup
)
func
Init()
{
defer
wg.Done()
a
=
"finally
started"
}
func
Simple()
string{
wg.Add(1)
go
Init()
wg.Wait()
//
do
something
else
return
a
}

30. channel
package
channel
var
(
a
string
ready
chan
bool
)
func
Init()
{
a
=
"finally
started"
ready
<-­‐
true
}
func
Simple()
string{
ready
=
make(chan
bool)
go
Init()
//
do
something
else
<-­‐ready
return
a
}

31. Producer
/
Consumer
func
producer(c
chan
string){
defer
close(c)
for
{
work
:=
getWork()
c
<-­‐
work
}
}
func
consumer(c
chan
string)
{
for
msg
:=
range
c
{
process(msg)
}
}
func
ProducerConsumer()
{
c
:=
make(chan
string)
go
producer(c)
consumer(c)
}

32. Producer
/
Consumer
func
producer(c
chan
string){
defer
close(c)
for
{
work
:=
getWork()
c
<-­‐
work
}
}
func
consumer(c
chan
string,
abort
<-­‐chan
Kme.Time)
{
for
{
select
{
case
msg
:=
<-­‐c:
process(msg)
case
<-­‐
abort:
return
}
}
}
func
ProducerConsumer()
{
c
:=
make(chan
string)
go
producer(c)
abort
:=
Kme.A|er(2*Kme.Second)
consumer(c,
abort)
}

33. Barber
Shop
Var
seats
=
make(chan
Customer,
2)
customers
:=
[]Customer{
"Al",
"Bob",
"Chad",
"Dave"
}
)
func
barber()
{
for
{
c
:=
<-­‐seats
fmt.Println("Barber
shaving",
c)
}
}
func
(c
Customer)
enter()
{
select
{
case
seats
<-­‐
c:
default:
fmt.Println("Customer",
c,
"Leaves")
}
}
func
BarberShop()
{
go
barber()
for
_,
c
:=
range
customers
{
go
c.enter()
}
}

34. version
build
test
get
install
fmt
…
build
-­‐-­‐race
(1.1+)
GO
COMMAND

35. h8p://golang.org/
h8p://tour.golang.org/
h8ps://code.google.com/p/go-­‐wiki/wiki/Projects
h8ps://groups.google.com/forum/#!forum/golang-­‐nuts
#go-­‐nuts
on
irc.freenode.net
h8ps://www.facebook.com/groups/golanggonuts