Go is a programming language created by Google that aims to be a simple, efficient, and concurrent language. The document provides an overview of the history and features of Go, including its support for garbage collection, concurrency, and ease of programming. Examples are given demonstrating how to write Go code, use interfaces and channels for concurrency, and connect to MongoDB. The document also lists several companies that use Go in production applications.

1. Go Introduc+on
U-am Gandhi

2. History of Go
• Robert Griesemer, Rob Pike and Ken
Thompson started the idea on Sep 21, 2007
• It became an open source project on Nov 10,
2009
• Go1 was released in March 2012

3. Why Go
• A good mix of fast compila+on, efficient
execu+on and ease of programming
• combines best of sta+c language and dynamic
language
• offers garbage collec+on, concurrency,
scalability
• Aims to be system programming language for
mul+ core machine

4. Comparison with C++, Java and
Javascript
C++ Java Javascript Go
Typesafe ✔ ✔ ✖ ✔
Garbage
Collec+on
✖
✔
✔
✔
Compila+on Slow Slow NA Very Fast
Concurrency ✖ ✔ ✖ ✔
Ease of
programming
✖
✔ ✔
✔
Efficiency Highest Slow Slowest Close to C++

5. Hello World
// hello.go
package main
import (
"fmt”
)
func main() {
fmt.Println("Hello World”)
}

6. Sample func+on
package main
import “fmt”
func split(sum int) (x, y int) {
x = sum * 4 / 9
y = sum - x
return
}
func main() {
var x, y, z int
fmt.Println(x,y,z)
fmt.Println(split(17))
}

7. How to Write Go Code 1/2
• Go tool is designed to work with open source
code maintained in public repositories
• Workspace
– src
– pkg
– bin
• export GOPATH=$HOME/go
• go install hello

8. How to Write Go Code 2/2
• go install sum (create and put
lib pkg)
• go install usinglib
• go get code.google.com/p/
go.example/hello
• go test sum

9. Object Oriented Go
• No classes, no inheritance
• go has duck typing
• structs are used for custom types, aggrega+on
• Interfaces, abstract type has methods
• Any custom type having same methods as
interface follows that (and/or other) interface
• Interface{}, empty interface is like void in C or
Object in Java

10. Interface
type Printer interface {
Print()
}
type MyFloat float64
func (f MyFloat) Print() {
fmt.Println(f);
}
func main() {
var a Printer
f := MyFloat(5.5)
a = f
}

11. Features 1/2
• Garbage collec+on
• Concurrency
• Packages
– fmt, net, os, +me, math, zlib
– h-p://golang.org/pkg/ has the exhaus+ve list
• Types
– bool, int, int8, int16, int32, int64, uint …, byte, float32,float64,
complex64, complex128
– const
• For loop only
• struct, access fields using dot
• Pointer but no pointer arithme+c

12. Features 2/2
• Slices
– s := []int{2, 3, 5, 7, 11, 13}
– len(s)
• Maps
– var m map[string]string
– m[“index”]
• Func+on values
f1 := func(x, y float64) float64 {
return math.Sqrt(x*x + y*y)
}

13. Concurrency
• go rou+nes
– Lightweight thread like rou+ne (may be one or more
thread)
• Channels and Buffered Channel
– Useful for sync between go rou+nes
– Send and receive to channel is blocking ( no sync needed)
• Range and close
– Range used itera+ng over channel
– Close used by sender aier sending all values
• Select
– Lets gorou+ne waits on mul+ple communica+on
opera+ons

14. JSON and Go
type Message struct {
Name string
Body string
Time int64
}
m := Message{"Alice", "Hello", 1290090}
b, err := json.Marshal(m)
-----------
b is now
[]byte(`{"Name":"Alice","Body":"Hello","Time
":1290090}`)

15. Web Server
type Hello struct{}
func (h Hello) ServeHTTP(
w http.ResponseWriter,
r *http.Request) {
fmt.Fprint(w, "Hello TechNext !")
}
func main() {
var h Hello
http.ListenAndServe("localhost:4000", h)
}

16. MongoDB Driver (mgo)
• Mgo Driver can be fetched using
– go get gopkg.in/mgo.v2
– go get gopkg.in/mgo.v2/bson
• Sample code to connect to mongo
session, err := mgo.Dial("localhost”)
collection :=
session.DB(”mydb").C(”mycollection”)
err := collection.Find(bson.M{”Name”:
“XYZ”}).One(&result)

17. Go In Produc+on
• Google is using in produc+on for
– h-p://golang.org
– Vitess system for large-scale SQL installa+ons
– Download server dl.google.com
• It delivers chrome binaries and apt-get packages
• Other companies using Go in produc+on
– InfluxData
– Canonical
– Heroku
– Iron.io
– Apcera
– Docker
– h-p://go-lang.cat-v.org/organiza+ons-using-go

18. References
• FAQ h-p://golang.org/doc/faq
• Installa+on h-p://golang.org/doc/install
• Code h-p://golang.org/doc/code.html
• Videos
h-p://blog.golang.org/go-videos-from-google-
io-2012
• Tour h-p://tour.golang.org/
• Efficiency BM - JSON Benchmarks

19. References
• h-p://www.javaworld.com/ar+cle/2080935/
scrip+ng-jvm-languages/go-google-go-a-
language-on-full-thro-le.html
• h-p://blog.golang.org/json-and-go
• h-p://www.drdobbs.com/open-source/geong-
going-with-go
• h-p://www.drdobbs.com/open-source/why-not-
go/240005062
• h-p://www.jellolabs.com/blog/why-golang-is-
ready-for-early-stage-startups.html

20. References
• h-p://stackoverflow.com/ques+ons/11462046/what-
is-the-niche-of-go-lang
• h-ps://code.google.com/p/go-wiki/wiki/
SuccessStories#
• h-p://stackoverflow.com/ques+ons/12168873/cross-
compile-go-on-osx
• h-p://ma-.aimoneo.net/posts/2012/11/27/real-life-
concurrency-in-go/
• h-p://www.golang-book.com/10
• h-p://ma--welsh.blogspot.in/2013/08/rewri+ng-
large-produc+on-system-in-go.html