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https://github.com/golang/go
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412 lines
9.1 KiB
HTML
412 lines
9.1 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<title>Go (January 12, 2010)</title>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="font-size-adjustment" content="-1" />
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type="text/css" media="screen, projection, print" />
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<script src="slidy.js" type="text/javascript">
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</script>
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</head>
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<body>
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<div class="background">
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<div class="header">
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</div>
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<div class="footer"></div>
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</div>
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<div class="slide titlepage">
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<div style="height: 135px; width: 480px; overflow: hidden; position: fixed; top: auto; bottom: 10px; left: auto; right: 0; ">
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<img src="../gordon/bumper480x270.png" style="margin: -135px 0 0 0;"/>
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</div>
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<!-- <img src="google.png" style="position: fixed; top: auto; bottom: 30px; left: 20px; right: auto;"/> -->
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<br/>
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<img src="../go-logo-white.png">
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<br/>
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<br/>
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<h1 style="padding-right: 0pt; margin-right: 0pt; color: #0066cc; font-size: 250%; border-bottom: 0px;">The Go Programming Language</h1>
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<div style="color: #ffcc00;">
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<h2>Russ Cox</h2>
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<!-- <h3><i>rsc@google.com</i></h3> -->
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<br/>
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<h3>Stanford University<br/><br/>January 12, 2010</h3>
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</div>
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</div>
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<div class="slide">
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<h1>Go</h1>
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<h2>New</h2>
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<h2>Experimental</h2>
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<h2>Concurrent</h2>
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<h2>Garbage-collected</h2>
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<h2>Systems</h2>
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<h2>Language</h2>
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</div>
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<div class="slide">
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<h1>Hello, world</h1>
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<pre>
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package main
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import "fmt"
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func main() {
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fmt.Printf("Hello, 世界\n")
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}
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</pre>
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</div>
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<div class="slide">
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<h1>History</h1>
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<h2>Design started in late 2007.</h2>
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<h2>Implementation starting to work mid-2008.</h2>
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<h2>Released as an open source project in November 2009.</h2>
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<h2>Work continues.<h2>
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<h2>Robert Griesemer, Ken Thompson, Rob Pike, Ian Lance Taylor, Russ Cox, many others</h2>
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</div>
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<div class="slide">
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<h1>Why?</h1>
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<h2>Go fast!</h2>
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<h2>Make programming fun again.</h2>
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</div>
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<div class="slide">
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<h1>Why isn't programming fun?</h1>
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<div class="incremental">
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<h2>Compiled, statically-typed languages (C, C++, Java) require too much typing and too much typing:</h2>
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<ul>
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<li>verbose, lots of repetition</li>
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<li>too much focus on type hierarchy</li>
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<li>types get in the way as much as they help</li>
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<li>compiles take far too long</li>
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</ul>
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</div>
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<div class="incremental">
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<h2>Dynamic languages (Python, JavaScript) fix these problems (no more types, no more compiler) but introduce others:</h2>
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<ul>
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<li>errors at run time that should be caught statically</li>
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<li>no compilation means slow code</li>
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</ul>
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</div>
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<h2 class="incremental">Can we combine the best of both?</h2>
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</div>
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<div class="slide">
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<h1>Go</h1>
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<h2>Make the language fast.</h2>
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<h2>Make the tools fast.</h2>
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</div>
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<div class="slide">
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<h1>Go Approach: Static Types</h1>
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<h2>Static types, but declarations can infer type from expression:</h2>
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<pre>
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var one, hi = 1, "hello"
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var double = func(x int) int { return x*2 }
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</pre>
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<h2>Not full Hindley-Milner type inference.</h2>
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</div>
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<div class="slide">
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<h1>Go Approach: Methods</h1>
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<h2>Methods can be defined on any type.</h2>
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<pre>
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type Point struct {
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X, Y float64
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}
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func (p Point) Abs() float64 {
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return math.Sqrt(p.X*p.X + p.Y*p.Y)
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}
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</pre>
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</div>
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<div class="slide">
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<h1>Go Approach: Methods</h1>
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<h2>Methods can be defined on any type.</h2>
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<pre>
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type MyFloat float64
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func (f MyFloat) Abs() float64 {
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v := float64(f)
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if v < 0 {
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v = -v
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}
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return v
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}
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</pre>
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</div>
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<div class="slide">
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<h1>Go Approach: Abstract Types</h1>
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<h2>An interface type lists a set of methods. Any value with those methods satisfies the interface.</h2>
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<pre>
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type Abser interface {
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Abs() float64
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}
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func AbsPrinter(a Abser)
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</pre>
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<h2>Can use Point or MyFloat (or ...):</h2>
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<pre>
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p := Point{3, 4}
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AbsPrinter(p)
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f := MyFloat(-10)
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AbsPrinter(f)
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</pre>
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<h2>Notice that Point never declared that it implements Abser. It just does. Same with MyFloat.</h2>
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</div>
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<div class="slide">
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<h1>Go Approach: Packages</h1>
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<h2>A Go program comprises one or more packages.</h2>
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<h2>Each package is one or more source files compiled and imported as a unit.</h2>
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<pre>
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package draw
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type Point struct {
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X, Y int
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}
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</pre>
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<pre>
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package main
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import "draw"
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var p draw.Point
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</pre>
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</div>
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<div class="slide">
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<h1>Go Approach: Visibility</h1>
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<h2>Inside a package, all locally defined names are visible in all source files.</h2>
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<h2>When imported, only the upper case names are visible.</h2>
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<pre>
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package draw
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type <span style="color: black;">Point</span> struct {
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<span style="color: black;">X</span>, <span style="color: black;">Y</span> int
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dist float64
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}
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type cache map[Point] float64
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</pre>
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<h2>Clients that <code>import "draw"</code> can use the black names only.</h2>
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<h2>“Shift is the new <code>public</code>.”</h2>
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</div>
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<div class="slide">
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<h1>Go Approach: Concurrency</h1>
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<h2>Cheap to create a new flow of control (goroutine):</h2>
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<pre>
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func main() {
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go expensiveComputation(x, y, z)
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anotherExpensiveComputation(a, b, c)
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}
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</pre>
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<h2>Two expensive computations in parallel.</h2>
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</div>
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<div class="slide">
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<h1>Go Approach: Synchronization</h1>
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<h2>Use explicit messages to communicate and synchronize.</h2>
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<pre>
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func computeAndSend(ch chan int, x, y, z int) {
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ch <- expensiveComputation(x, y, z)
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}
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func main() {
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ch := make(chan int)
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go computeAndSend(ch, x, y, z)
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v2 := anotherExpensiveComputation(a, b, c)
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v1 := <-ch
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fmt.Println(v1, v2)
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}
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</pre>
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<h2>Notice communication of result in addition to synchronization.</h2>
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</div>
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<div class="slide">
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<h1>Go Fast: Language</h1>
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<h2 class="incremental">Static types: enough to compile well, but inferred much of the time.</h2>
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<h2 class="incremental">Methods: on any type, orthogonal to type system.</h2>
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<h2 class="incremental">Abstract types: interface values, relations inferred statically.</h2>
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<h2 class="incremental">Visibility: inferred from case of name.</h2>
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<h2 class="incremental">Concurrency: lightweight way to start new thread of control.</h2>
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<h2 class="incremental">Synchronization: explicit, easy message passing.</h2>
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<br/>
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<h2 class="incremental">Lightweight feel of a scripting language but compiled.</h2>
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</div>
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<div class="slide">
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<h1>Compile fast</h1>
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<div class="incremental">
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<h2>Observation: much of the compile time for a source file is spent processing
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other, often unrelated files.</h2>
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<h2>In C: <code>a.c</code> includes <code>b.h</code>, which includes <code>c.h</code>, which includes <code>d.h</code>.
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</h2>
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<h2>Except that it's more often a tree instead of a chain.</h2>
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<h2>On my Mac (OS X 10.5.8, gcc 4.0.1):</h2>
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<ul>
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<li>C: <code>#include <stdio.h></code> reads 360 lines from 9 files.
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<li>C++: <code>#include <iostream></code> reads 25,326 lines from 131 files.
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<li>Objective C: <code>#include <Carbon/Carbon.h></code> reads 124,730 lines from 689 files.
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</ul>
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<h2>And we haven't done any real work yet!</h2>
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<h2>Same story in Java, Python, but reading binaries instead of source files.</h2>
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</div>
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</div>
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<div class="slide">
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<h1>Implementation: Summarize Dependencies</h1>
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<pre>
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package gui
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import "draw"
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type Mouse struct {
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Loc draw.Point
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Buttons uint
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}
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</pre>
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<h2>Compiled form of <code>gui</code> summarizes the necessary part of <code>draw</code> (just <code>Point</code>).</h2>
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</div>
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<div class="slide">
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<h1>Implementation: Summarize Dependencies</h1>
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<h2>Compiled form of <code>gui</code> summarizes the necessary part of <code>draw</code> (just <code>Point</code>). Pseudo-object:</h2>
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<pre>
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package gui
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type draw.Point struct {
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X, Y int
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}
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type gui.Mouse struct {
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Loc draw.Point
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Buttons uint
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}
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</pre>
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<h2>A file that imports <code>gui</code> compiles without consulting <code>draw</code> or its dependencies.</h2>
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<h2>In Go: <code>import "fmt"</code> reads <i>one</i> file: 184 lines summarizing types from 7 packages.</h2>
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<h2>Tiny effect in this program but can be exponential in large programs.</h2>
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</div>
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<div class="slide">
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<h1>Compilation Demo</h1>
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<h2>Build all standard Go packages: ~120,000 lines of code.</h2>
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</div>
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<div class="slide">
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<h1>Go Status</h1>
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<div class="incremental">
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<div>
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<h2>Open source:</h2>
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<ul>
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<li>released on November 10, 2009
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<li>regular releases (~ weekly)
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<li>all development done in public Mercurial repository
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<li>outside contributions welcome
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</ul>
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</div>
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<div>
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<h2>Portable:</h2>
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<ul>
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<li>FreeBSD, Linux, OS X (x86, x86-64)
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<li>(in progress) Linux arm, Native Client x86, Windows x86.
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</ul>
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</div>
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<div>
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<h2>Still in progress, experimental. Yet to come:</h2>
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<ul>
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<li>mature garbage collector
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<li>generics?
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<li>exceptions?
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<li>unions or sum types?
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</ul>
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</div>
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</div>
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</div>
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<div class="slide titlepage">
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<h1>Questions?</h1>
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<br><br>
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<center>
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<img src="../gordon/bumper640x360.png">
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</center>
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<br><br>
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<div style="color: #ffcc00;">
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<!-- <h3><i>rsc@google.com</i></h3> -->
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</div>
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</div>
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</body></html>
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