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Google’s GoIntroduction to the next “C” language!
S G Ganesh
Agenda Introduction to Go (What is “Go”?) “Hello world” in Go Examples for “getting a hang of” Go Examples using some novel features Implementation status Resources Let’s Go!
First things first: Setting the stage It’s not possible to cover all details of a new language in a
45-mins presentation We’ll quickly cover most important aspects of Go Can’t drink ocean in a day – let alone in an hour!
No one is an “expert” in Go yet Creators of the language are the only experts right now I am an early adopter and got hooked-on to the
language I am making this presentation based on my experience
For many questions, there are no right or wrong answers: Go is still an evolving language and answers might
change!
So, what’s all the buzz about? Go: new programming language announced by Google (Sep 09)
Created lots of excitement in the programming community
Many tout it as the next C language ‘C’ evolved from ‘B’; many languages are named as ‘D’, or
want to be the ‘D’ language But nothing has made the cut so far; “Go” might (or will it be
“Gone” in a few years ;-) )
Is there substance behind hype? Yes, a lot! Most system programmers find it very good Go won Tiobe’s ‘language of the year award 2009’
Tiobe is a programming language popularity index: http://www.tiobe.com/
Latest status (march 2010)
Okay, so what’s Go? Go is a new, experimental, concurrent, garbage-collected,
systems-programming language. New & Experimental: Go is still at experimental stage
with tools, packages etc. still in development. No production system implemented using Go till now
Concurrent: Supports 'communication channels’ for concurrency - Communicating Sequential Processes (CSP).
Garbage-collected: The memory is automatically garbage collected
For systems-programming: Intended for writing things like compilers, web servers…
Still, we can use it as a general purpose language.
Who’s behind Go? Robert Griesemer, Ken Thompson (of Unix
fame), and Rob Pike are the creators of the language. All three are well-known in programming community
This is how things fell in place: Go project was started around May 2007. Ken Thompson
wrote a Go compiler and runtime from scratch. By mid of 2008, working compiler and runtime was ready. Ian Lance Taylor and Russ Cox joined Go team in 2008. Ian
Taylor implemented GCC front-end for Go.
Why a new language? This description is as given by the creators
No major sys. programming language came-up in last decade. But much has changed during the last decade(s)
Libraries becoming bigger with lots of dependencies Internet and networking is becoming pervasive Client/server systems, massive clusters used today Multi-core processors becoming mainstream.
Systems programming languages were not designed with these in mind.
Other reasons construction (enterprise software) has become very slow OOP using inheritance hierarchies not effective
Goals of the language Efficiency and ease of use:
Efficiency of C, but ease like Ruby. Performance: within 10%-20% of equivalent C
Safe to use: Both type-safe as well as memory-safe.
Concurrency: Good support for concurrency and communication
Garbage Collected: "Attempts" to build an efficient, and latency-free Garbage
Collection mechanism. High-speed builds:
Fast compilation & linking
Some important capabilities of Go Simplicity: GO has a clean and concise syntax
Characteristic of Google products For example, light-weight type system
Use it to believe it
Separation of interface and the implementation I know it’s often misused statement, but Go has it! Arguably a novel feature of Go
Goroutines Is based on CSP: much safer than lock-based, like Java
And more: E.g. Reflection (yes! but this is systems prog. lang!)
Enough theory, lets see examples!
All programs in Go should be in a package, its “main” here
We import “fmt” package for using Printf function Execution starts with ‘main.main()’ function Functions have “func” keyword Printf is in fmt package
Now we’ll find factorial of a number
Lack of declarations “fact” and “i” inferred as “ints” from init value 1 because of :=
“for” loop is the only loop construct supported in Go Others like “while” are variations of “for” An example of minimal features
Note the lack of semi-colons Have to use only if “necessary”
Looks like C, but not C!
Go has elegant declaration syntax See how arguments are passed and returned Not like C: it is infamous for its declaration syntax
Can return multiple values from functions See swap for similar functionality in = operator Example for “orthogonal” language features
Built-in support for features like maps
Maps are built-in, so no need to import Initialized with pair separated by “:”
“range” keyword is useful for traversal Using a for loop Works for slices, strings etc. (“orthogonal” feature)
Functions as first class objects
Functions are first class objects in Go We can have
“function literals” (similar to “closures” in functional languages) for example
Structures
Structs are declared with type keyword We can have struct literals
Created in heap And print struct members using %v in Printf
Methods
Methods are implemented by specifying the struct name before the method name
Interfaces: A novel feature Interfaces specified with
‘interface’ keyword Not same as in C#/Java
The structs doesn’t have to say it implements an interface Any struct that implements
the methods as specified by any interface satisfies that interface
Strict static type checking & “duck typing”!
Goroutines: easy & safe multithreading
Goroutines are functions executing in parallel in the same address space in stack
They communicate using “channels” (based on CSP) Cleaner, simpler and less-bug prone than using locks
This shows an example* of how a Sort on big list can be done in parallel with some other computation
We haven’t covered a lot! Important features not covered because of limited time
reflection, embedding structs (aka inheritance), package construction etc.
Lots of libraries already implemented math, crypto, networking, regex, OS, testing, html gen….
Garbage collection & Go runtime capabilities Currently mark-and-sweep collector, but better ones under
construction Small runtime: GC, channels, stack allocation, goroutines
etc.
Implementation status Currently compiler tool-chain available for Mac & Linux
No “official” windows port; “unofficial” old ports exist Compilers: GCC implementation and a stand-alone implementation You can download the compilers/tools from this website & try it It’s open source (BSD license): We can contribute!
Lots of work going on in libraries and improving the existing tool chain Frequent builds & releases, quick response times etc.
Many features & tools still lacking in Go For example, generics and debugger tool
Resources Go websites:
Official: www.golang.org (web server implemented in Go!) Unofficial: http://go-lang.cat-v.org/
Want to learn Go? No “books” yet Read "Effective Go” (http://golang.org/doc/effective_go.html)
tutorials available online Tech talk (http://www.youtube.com/watch?v=rKnDgT73v8s) Join go-nuts mailing list [email protected]
You can try (compile & run) Go programs online! This is really useful: http://ideone.com/
Q & A time
