A First Look at Google's Go Programming Language

A First Look at Google's Go Programming Language

• 1.
  Google’s Go Introduction tothe next “C” language! S G Ganesh
• 2.
  Agenda  Introduction toGo (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!
• 3.
  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!
• 4.
  So, what’s allthe 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)
• 5.
  Okay, so what’sGo?  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.
• 6.
  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.
• 7.
  Why a newlanguage?  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
• 8.
  Goals of thelanguage  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
• 9.
  Some important capabilitiesof 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!)
• 10.
  Enough theory, letssee 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
• 11.
  Now we’ll findfactorial 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”
• 12.
  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
• 13.
  Built-in support forfeatures 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)
• 14.
  Functions as firstclass objects  Functions are first class objects in Go  We can have “function literals” (similar to “closures” in functional languages) for example
• 15.
  Structures  Structs aredeclared with type keyword  We can have struct literals  Created in heap  And print struct members using %v in Printf
• 16.
  Methods  Methods areimplemented by specifying the struct name before the method name
• 17.
  Interfaces: A novelfeature  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”!
• 18.
  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
• 19.
  We haven’t covereda 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.
• 20.
  Implementation status  Currentlycompiler 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
• 21.
  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 gonuts@googlegroups.com  You can try (compile & run) Go programs online!  This is really useful: http://ideone.com/
• 22.
  Q & Atime
• 23.
  So what areyou waiting for?  Lets Go!