SMITA VIJAYAKUMAR

Go ProgrammingINTRODUCTION TO

smita@exotel.in

AgendaModern Compute Environment

Focus: What Problem does it Solve?

History

How is it Achieved

For C Programmers - Major Differences

Challenges in Modern Compute Landscape

EnvironmentMulti-CoreNetworked SystemsComputational ClustersWeb Programming ModelThousands of ProgrammersSame code baseScale of Development

Legacy LanguagesLanguage Feature ComplexGarbage CollectionMissing language support for ConcurrencyCompilation TimesDependency Management

Programmers digress from the real task!

Crux:

Focus

“Go’s purpose is therefore not to do research into programming language design; it is to improve the working

environment for its designers and their coworkers.”–Rob Pike

(Co-Designer of Go and Distinguished Engineer at Google)

History

HistoryInception: 2007Go 1.0 released in 2012Rob Pike, Ken Thompson and Robert Griesemer

HistoryBinary = 2000 X C++ Source BytesUnused Library IncludesConditional IncludesExtremely Slow Compilation

Even on Distributed Compilation System!

Desired FeaturesLight WeightIncrease Programmer EfficiencyCompiled LanguageConcurrencyGarbage CollectionStatically Typed

How is it Achieved?

HowNo unused import packagesDependency graph is preciseNo dependency cyclesOnly exported data availableOne object both exported and complete data

How40X faster compilation times than C++!

Differences between Go and C

SyntaxImport paths are URLsCleaner syntax

Syntax//Ctypedef struct A { int a; char b; }

//Gotype A struct { a int b char }

Syntax/* C *///Expression Syntaxint main(int argc, char *argv[])

// The Clockwise-Spiral Rule in C syntax parsingint (*(*fp)(int (*)(int, int), int))(int, int)

/* Go */// Type Syntaxfunc main(argc int, argv []string) int

//Left to rightf func(func(int,int) int, int) func(int, int) int

Syntax//Go can also return multiple value from function func ReadFile(r io.Reader) (num int, err error) { ...}...n, err := ReadFile(r)

Syntaxpackage util//Counter is visible when package is imported var Counter int

//name is not var name string

//Seenfunc ThisIsAlsoAvailable() error { }

//not seenfunc thisIsAPrivateFunction() error { }

ScopesUniverse (language identifiers)PackageFileFunctionBlock

SemanticsNo pointer arithmeticsNo implicit numeric conversionsArray bounds are always checkedtypes are not type aliases

type X int // X and int are distinct

Interface typesReflectionType switch

ConcurrencyGo RoutinesChannels - Communication Pipes

Concurrency

Light-weight threads of executionManaged by Go RuntimeRun concurrently with other go routinesExample

Shared resource manager QuerierDB Readeretc...

Go Routines

Concurrencypackage main import “fmt”

func myPrinter(str string) { fmt.Println(str)}

func main() { myPrinter(“one”) go myPrinter(“maybetwo”) go myPrinter(“maybethree”)}

//Output one maybetwo Maybethree

//Orone maybethree maybetwo

//Orone...

Concurrency

Shared pipes connecting concurrent go routinesChannels

Concurrencypackage main

import "fmt”

func main() { messages := make(chan string)

// Send a value `channel <-` go func() { messages <- "ping" }() //continued

//continued // Receive a value `<-channel` msg := <-messages fmt.Println(msg)}

//Output ping

GCEasier for ProgrammerNo overhead of memory allocation and freeingNo explicit memory freeing

InterfacesSet of methodsMethods on any typeData types implementing all methods satisfy

Thank You!SMITA VIJAYAKUMARsmita@exotel.in