Placeholder Image

字幕列表 影片播放

  • >> PIKE: I’m going to talk about the Go Programming Language, which is going to be--we

  • hope going open source on November 10th, which is in just a couple of weeks. This talk is

  • a little bit before then, so some--there are some future tense for things like links and

  • so on, but everything should be as recorded by the time we actually go public with this

  • stuff. You can see we have a website were setting up, which will be the public domain,

  • public viewable domain for that. So, what is it? Well, I’m can talk about all these

  • pieces but it is new, an experimental, concurrent, garbage-collected, systems, language. Experimental

  • because were not--we don’t believe this is the answer to everything, but were playing

  • and we think it’s gotten to the point where it’s time we should probably tell the world

  • about it. It’s concurrent because it’s really important in the modern world. It’s

  • garbage-collected because we have an opinion on that stuff, which I’ll talk about it

  • quite a bit later. And it’s a systems language in the sense that we intended to be written,

  • to be used to write things like Web servers and other, you know, system aspects like that.

  • You have more control over some things and you have another languages like, say, Java

  • or Python, but it’s--it works like a systems language when you use it. On the other hand,

  • it's very good at things we find for things like front-ends or just general programming.

  • So, although, it’s designed as a systems language, it has much broader use than just

  • that. I can't give a talk without showing you, "Hello, world." There’s "Hello, world"

  • with the "world" being Japanese, which I want to attempt to pronounce. But you can see that

  • it looks vaguely C like although there’s some "weirdnesses" about it. I won’t talk

  • about what those "weirdnesses" are. Who’s involve? Well, I’m giving the talk but it’s

  • by no means my project. There’s a bunch of people involve and I want to make sure

  • everyone’s cleared. Some of the names are really important here. Robert Griesemer, Ken

  • Thompson, and I started talking about doing something to solve the problems we were seeing

  • with other environments. Some time around two years ago in late 2007, we played mostly

  • at the Wade Park for a few months to figure some things out. But by middle of 2008, we

  • had a toy compiler and things were starting to look interesting and we started working

  • on the stuff for real. And around that time, Ian Taylor joined and Russ Cox joined, and

  • the five of us did the most of the work, but weve had a lot of help from a lot of people

  • that this slide is too small to name. So I just make--I want to make it clear this is

  • a collaborative effort and the collaboration is growing. Why? Well, the reason is things

  • were just taking too long: too long to compile, too long to build, too long to think about.

  • We want a program fast. We want a program fun. And to make programming fun, you have

  • to find ways to speed things up and make things work better, not just the code itself but

  • the process of writing the code needs to be efficient. So what’s happened? Well, you

  • know, program used to be fun. What went wrong? Well, it’s interesting there's been really

  • been no new major systems language in at least 10 years or could be longer. But in that decade,

  • a lot has changed. The libraries have gotten bigger. Professional programming has, to a

  • larger extent, become a layering process, and so we layer more and more stuff on and

  • we also broaden out the base. The libraries got really big. There’s a lots of them.

  • They communicate with dependencies to one another and so the force has become a thicket,

  • and at some times it’s kind of hard to cut your way through it. Networking has pretty

  • much taken over the world, that's the way to think about computing. The old son thing

  • about the network is the computer is pretty much true today, but the languages don’t

  • really reflect that. There’s a lot of client/server kind of stuff especially in the systems base.

  • Languages don’t really help you there too directly. Of course, were talking about

  • massive compute clusters now and again, the languages are designed for single processors.

  • They don’t really work very well in that model. And on a related note, multi-core CPUs

  • are taking over, too. It’s getting harder to buy a high-end computer with only one processor.

  • It tends to be multi-core, sometimes multi-chip/multi-core. And again, the languages that were using

  • weren't really designed with that kind of stuff in mind. And it’s also gotten--I think

  • this is the thing that finally pushed us to try to do something. It’s just gotten to

  • slow to build software. The tools are slow. They have a hard problem to do, but they still--theyre

  • tend to be slow and theyre getting slower. The computers have speed up enormously but

  • the software development process, if anything, has gotten slower over the last ten years.

  • The dependencies are uncontrolled and the languages don’t help you control them, so

  • you tend to spend a lot of time maybe building things you don’t even need but you don’t

  • know it, can’t prove it. The machines have also stopped getting faster. Theyve gotten

  • more but they haven’t gotten faster. There are more processors, there are more of them,

  • but the actual clock speed has hardly changed in the last few years and Moore's law, to

  • some extent, is peering out and yet the software gets bigger and bigger and bigger. And so,

  • somehow, it feels like if we don’t do something, then software construction is just going to

  • become unbearably slower and we need to think about the process of making it fast again.

  • Robert Griesemer observes that a lot of the interesting work in languages in the last

  • few years is been because a lot of the people using these standards systems languages like

  • C, C++, even Java are finding the clamp--the type systems are very sort of clumsy or hard

  • to work with. And as they go to the dynamic languages: the Pythons, the Ruby’s, even

  • the JavaScript of the world, they have a lot more fun because the type systems don’t

  • get in the way so much at least as long as the program keeps running. And so, the challenge

  • here is to try to deal with this. You want typing. You want a good typing because it

  • makes programs robust, but it can be done badly. And we are given in some ways, there

  • is--if not done badly, it should at least be done the different way. Sometimes good

  • ideas, in principle, make bad practice. And a good example of that is the "const" keyword

  • in C and in C++, which was very well intentioned and seem to address the real need in making

  • program safer, but it tends to make programming awkward in a lot of ways, so this isn’t

  • worth the benefit you get back from using. Also, there is this notion of everything being

  • a type hierarchy in object-oriented programming. And yet, the types in large programs don’t

  • really naturally fall into hierarchies. We find the way to make them fit, but it’s

  • a bit of a struggle. In program, we spend so much time re-factoring a code, juggling

  • type trees around, and that has very little to do with the implementation and lot to do

  • with the way the language is forcing you to think. We’d like to be--we’d like to sort

  • of step back from that model. And in short, therefore, with the way type systems work

  • today, you can be productive or you can safe, but you can’t really be both. And that seems

  • like a shame; we should be able to fix that. So, why a new language? Why don't we just,

  • you know, fix what we've got? Well, some of the problems are just fundamental to the way

  • the languages are thinking, the way the type systems work, the way theyre compiled,

  • the way dependencies are managed. The languages themselves have these problems endemic in

  • them, and to fix them, you have to rethink the languages itself. For instance, the libraries

  • can’t help you, because adding anything to try to fix some of these problems is going

  • in the wrong direction. There’s too much already. We need to trim down, cut the fat,

  • and make things cleaner. Fixing it by adding software isn’t going to do it. You have

  • to sort of step aside and do something separate. And so, we decided: Robert, Ken, and I couple

  • of years ago that we need to start over. Just take a step away and think about the way programs

  • are written and constructed and try to make a language that makes that process a lot easier.

  • So, it’s a new language. What are the goals of this language? The sort of short version

  • of the story is we want the efficiency of a statically compiled language; that means

  • truly compiled language, but the ease of programming of a dynamic language. And I think we have

  • come pretty close to achieving that. You can decide for yourself as we go on. Safety is

  • critical. It’s critical to the language: the type-safe and then the memory-safe. It’s

  • important that a program not be able to derive a bad address and just use it, that a program

  • that compiles is type-safe and memory-safe. That’s a critical part of making robust

  • software and we just--that’s just fundamental. We want good support for concurrency. I’ll

  • talk a little bit about that. Communication, I’ll talk about that, too. Those are tools

  • that can help you build software that runs in the network or in multi-core CPUs. We want

  • to build--were going to garbage like to think, because a lot of the bookkeeping that

  • goes on inside modern programming, especially in C and C++, has to do with memory management.

  • And that can be totally automated. And we believe, "believe" is the word, that you can

  • do that efficiently and, essentially, latency-free that the garbage collection technology is

  • advance to the point where a garbage collected systems language actually makes a lot of sense,

  • and so we’d like to do that. And also, we’d like the compiler to just run fast. Everyone

  • knows this slide and there’s some truth to it. You know, you spent too much time waiting

  • for compilers. So, let me give you a compilation demo here. This is a directory of Go code. If you look

  • in here, there’s a 1,300 lines, so I make clean, and then I’ll just do a major. There,

  • I just built the last library. That’s compiled, efficient code, clean again. In case you wonder

  • if I can type, okay, time make. Okay. So that’s what two--well, pretty accurately, 200 milliseconds

  • real time to build the library. That feels about right. For the last years or so, those

  • who’s working with Go had been getting used to 100 millisecond builds on one machine.

  • That’s running on my laptop, by the way. That’s not some distributed thing. That’s

  • one processor, one build. And just to prove it a little better, let me make clean. This

  • is the complete Go source tree. All of the libraries written in Go, there’s something

  • of order. I think it’s about 120, 130,000 lines. So, included in here are regular expressions,

  • flags, concurrency primitives, the run-time, the garbage collector, pieces--oh it’s finished.

  • Okay. So that was a one processor. I couldve paralyzed it a bit better. But that’s eight

  • seconds. That feels long to me now. That’s a long time because this is all the software

  • that’s there and, you know, it’s a long time to build--you can get a lot done with

  • that much time. Just to remind you, then we go back here, that’s what you want to see.

  • You want to have character return time for your compilations, and it can be done. So

  • let me get that set for later and well go back to this. Okay. So, we think weve

  • got fast compilation and I can’t tell you how much--what a difference that makes to

  • your life. Sometimes hours and hours to go by when people finally showed up to my office

  • and say, "Hey, you didn’t answer my mail." I have to look in the mail and actually getting

  • work done. Okay. So to do this language, we had to have some principles on which is built.

  • And there are actually some fundamental principles in here that in some ways, I think, differ

  • from some of the other languages out there, so I'd like to go through them. One of them

  • is that we try as much as possible to keep the concepts orthogonal. For instance, in

  • the interface surface, I’ll talk about the concept of implementation versus interface

  • or completely orthogonal. Theyre two separate things, they don’t interact and you don’t

  • define them together, you define them in separate objects and that makes a lot of stuff cleaner.

  • And in practice, this is because a few orthogonal features that cover the space work a lot better

  • in practice than a lot of overlapping lines. That’s a principle that’s a little vague

  • but I think, I think you know what I’m getting at. The grammar is very regular and very simple.

  • It’s actually conflict free and can be parsed without a symbol table, there’s no conflicts

  • in it. That makes it easier to write tools, like IDEs or editor plug-ins, and things like

  • that, debuggers because the parsing line is understanding and the program is actually

  • pretty straight forward. We try to reduce the typing. What I mean by that is that we

  • want the language to work things out. You tend to type too much when youre programming

  • in modern object or in languages. You tend to write statements like that. That’s literal.

  • If you change "Foo" for a much longer word, that’s an example I found in some code I

  • want to end. And I just, you know, "Foo" should just go away. You shouldn’t have to type

  • all those "Foos," that’s crazy. So you want to get rid of the bookkeeping, you want the

  • type system to automatically works the "Foo," but you still want to be safe. You want it--you

  • want it to be type-safe, but well handled. And also, not only you don't want to reduce

  • typing, you want to reduce typing. You want to type to sort of melt away into the background.

  • You want it to be clear, you don’t want to type hierarchy, we don’t want to type

  • hierarchy, and then I'll show you some examples on why that actually helps. We just think

  • the program by constructing type hierarchies, is not the way to go. We have an alternate

  • world. However, Go is a profoundly object-oriented language. Arguably, more object-oriented language--more

  • object-oriented than, say, Java or C++, and I’ll show you why. So, the big picture,

  • there’s some fundamentals. We have a clean concise syntax. We have very lightweight type

  • system. We got rid of implicit conversions, because theyre all inconvenient. They tend

  • to cause a lot of confusion particularly in the old C rules for things like the, you know,

  • the usual conversions are actually not all that usual, and now these got right. So everything

  • is very clear and very clean on what’s going on in the page. Of course, when you know the

  • conversions, you tend to do a lot of casting or conversions by hand and that’s messy,

  • so we address that by changing constants pretty profoundly. I’ll talk about that in a little

  • bit. You'll never--you won’t see "0x80ULL" in a Go program. The ULL is completely pointless,

  • you can’t even say it, numbers are just numbers. And there’s a strict separation

  • between the interface and implementation. That’s part of keeping the concept orthogonal

  • and the type system clean. So there’s a runtime, there’s a garbage collection, there’s

  • a good support for strings, maps, associate raise, that kind of thing, and also the communication

  • channels, which well talk about, and then there’s really strong support for concurrency.

  • It’s actually some of the best concurrency stuff, I think, that’s out there. It's really

  • good. And then, there’s a package model, which I won’t talk very much about because

  • it’s kind of takes a lot of explaining. But the notion here is that inside the packages,

  • everything is explicit. What you depend on is explicit. Compiler rejects your program

  • if you put in the dependency you don’t need. It’s all very clean and so, it makes tools

  • easy to understand dependencies and then it makes the builds guaranteed minimal. So, that

  • helps enormously. Regarding the dependencies, the linking going faster, the compilation

  • can go faster but--and there’s actually a notion in here that I think is important.

  • The compiler actually pulls the transitive dependency information up the tree as it’s

  • compiling, simply to reduce the number of files it has to look at, which in turn speeds

  • up the compilation process. So, if you have a program, A.go, that depends on B.go that

  • depends on C.go, which is pretty standard kind of thing. You--in the usual way, you

  • have to compile them in reverse order, because you got to build the dependent stuff before

  • the depending stuff. But the point is when you go to compile, A.go, it doesn’t need

  • to compile C. It doesn’t need to look at C.go at all. It doesn’t even need to look

  • at the object code for C, because everything that B need from C has already been pulled

  • up into B.go. And that doesn’t sound like a big deal, but when youre at scale, it’s,

  • literally, exponentially faster at building software when you get in to this huge dependents

  • situation. For concurrency, we sort of have a model. I’ll touch on it today. There’s

  • a lot more stuff online about it. But we have a suggestion for how to write systems and

  • servers as concurrent garbage-collected processes, which we called, goroutines. Well have

  • good support from the language and the run-time. We change the name because they're slightly

  • different from what you're used to. If you use the words like thread or process or goroutine,

  • that’s not quite the same, so we have our own word, goroutine. The language takes care

  • of managing the goroutines and managing the memory that they use and the communication

  • between them. Stacks grow automatically. That’s taken care of by the language. You don't have

  • to declare how big the stack is going to be. If it needs a bigger stack, it gets the bigger

  • stack. If it needs a smaller stack, it uses less memory. And those stacks are multiple--I’m

  • sorry, the goroutines are then multiplexed on the threads. That’s all done automatically

  • for you and [INDISTINCT] transparently. And, one of the feature--one of the reasons for

  • needing garbage collection is that concurrent programming is very hard without garbage collection,

  • because as you hand items around between this concurrent things, who owns the memory? Whose

  • job is it to free it? And there’s a lot of bookkeeping involved that the--if the language

  • or the system doesn’t take care of that for you. So you need garbage collection to

  • make concurrency work well. On the other hand, you need--to get the garbage collection to

  • work well, you need a language that makes garbage collection a feasible thing to do,

  • which is another argument for doing a new language. So, I don’t have time to explain

  • all of Go to you. It’s a significant language, it’s--I’d say probably bigger than C but

  • not as big as C++. Enough time to go through all of it, but I want to give you the flavors.

  • I’m going to go through about a dozen slides that are--I hope sort of representative of

  • the kinds of things that go on, but I’m going to leave out quite a bit. Lexically,

  • it looks a little bit like C, actually a little more than like C than this slide, we let you

  • believe. There’s usually a keywords involved, introducing things, you see const and var.

  • Const, that means it’s a constant, not--it’s not the const keyword from C, it’s completely

  • different meaning. It just means, in the first line there, N is a constant 1024. And it’s

  • just a number, it’s not an int, it’s not a float, it’s not an unsigned int, it’s

  • just a number. And there’s a const string and you can see we support Unicode just fine.

  • In fact, the language requires that the input be UTF-8 encoded. And then, you can declare

  • variables with the "var" keyword in the usual way. Youll notice--I’m quite use to it

  • now, but for C programmers this looks backwards, because in C, you put the float before the

  • X and the Y, but they're reversed and there’s a long explanation on the web about why we

  • did this. But the fundamental reason is it actually has been cleaner because, for instance,

  • in that declaration, X and Y both have type float. Whereas, if flip it around put the

  • keyword first, things get a little funnier. And you can see what the C version of that

  • will look like. You'd have to reproduce the star. So this is simplification you get. There’s

  • characters, Unicode supports, and stuff like that. Then we in this example, was not really

  • an example, just some lines of code, there’s a type struct, T, that's defined. It's got

  • a couple of fields within if they're both integers. Then we declare a variable, t0,

  • which is a new T. That should be pretty familiar what that means. But there’s too much typing

  • going on there. So the next line there, T1 := new(T), that’s an old notation from some

  • languages that I work with before. What that call and equals means is declaring the initialized.

  • So that--those two lines are equivalent. Var t0 *T = new(T), it has too many Ts in it.

  • We can get rid one of them by just having the type of t1 we derive from the expression

  • that’s used to declare and initialize it. And youll see that used a lot in Go code.

  • The var doesn’t show up nearly as much as the colon equals notation. Their control structure

  • is they're actually quite interesting control structures--just the first blast through,

  • pretty the same as C. Theyre actually quite richer, but the basics are the same. The main

  • difference is syntactic. The braces are required on the blocks and there’s no parenthesis

  • on, for instance, the conditional expression inside an "if" statement. That's just to clean

  • up the grammar. So here’s a real program. It’s not "hello, world," it's echo this

  • time, but it’s got all the parts. The first time the code says, "package main," that has

  • some meaning in the language about me get muted. We're thinking about simplifying a

  • few things but at least for the moment it's "package main." then you can see there's a

  • function called "main" is declared down below. And the program begins execution by starting

  • "main.main" initialization inside. There’s a declaration of the flag from the flag’s

  • package, so that makes minus N, turn off new lines from echo. It’s not strictly a UNIX

  • echo because it’s got real flag parsing, but it’s essentially the same. Those import

  • statements say, "Were going to use package OS," which does some stuff for us and were

  • going to use the flag package, obviously. Now, the way the initialization stuff works

  • is that in-flag variable will be initialized before "main" starts executing. All the global

  • variables get initialized by--and they can be initialized by arbitrary complex stuff

  • before "main" starts. So then in "main," we do the flag parts that get the command line

  • pulled apart. And then we just loop over the arguments which are now the [INDISTINCT] the

  • flag package, and it’s the obvious loop accumulating. You can see += on the string

  • there to append to the string, and stuff like that. And then at the bottom, the flags are

  • actually pointers in Go, the flag package makes them pointers. So the *nFlag, which

  • is a Boolean, is false. Then, you add a new line to the end of it. And then finally, you

  • do a method called "os.Stdout" to get the open-up. So, although, pretty much every line

  • in here is different from what youve seen before, it should be perfect and clear what’s

  • going on. I don’t think youll find that a mysterious program. So let’s talk about

  • constants. I said they are a little different. Constants in Go are what we like to think

  • of as sort of type-less. They have no type. They have no size. Theyre just numbers

  • or strings. You can have constants and strings in Booleans, but numbers are the interesting

  • case. So in this little snippet here, is just some constants being used. We start by defining

  • a type TZ for timeZone, which is an integer. And then, we declare some constants, UTC and

  • EST. We declare them to have type TZ and assigned to those initial values. You can clear what’s

  • going on there. The parenthesis around the const is distributing the const declaration

  • introducing keyword across the elements inside that declaration. So that’s the same as

  • saying, "Two const declarations with the two variables in them." Youll see later on

  • the next page here that actually matters that you can group them like this, because there’s

  • a thing called iota, which is an enumerating constant. It literally--for each const declaration,

  • counts which element youre on. At every semicolon, it increments. Starts at zero on

  • the next line, it's one, the next line is two. And so, here you can see, were declaring

  • bit0 and mask0 to be uint32s, and the first one is set to one shifted up iota. Iota starts

  • at zero in every const. So that’s one shifted up zero and one shift zero minus one. So that’s

  • a bit and a mask. And then the next line does it again, but now iota has gone up to one.

  • So we get the next guy in the sequence. You can see how to use that to build enumerated

  • constants but this is a slightly richer example. And again, to reduce typing, if you want,

  • you can just say, declaration, like the third line there with the semicolon and what that

  • says is, "Just keep doing what I did." Take the declaration initializer from the previous

  • line then pretend that you just type that here. And so, if you want to declare a new

  • ready constant, you can say, const open parenthesis inum0 equals iota semicolon and then you just

  • go inum1 semicolon, inum2 semicolon and all the way down the page. And just have them

  • declare sequential numbers for their constants. One very important properties of these numeric

  • constants in Go, is it there are arbitrary precision. So, here’s a const, the logarithm

  • of 2, you can see that’s got like 40 or 50 decimal places in it, which is more than

  • even a float 64 can represent. But that’s a valid declaration, because theyre just

  • numbers. And then the next line, we can actually compute log2, log base 2 of E as one over

  • log of 2, and that’s a precise division because it’s happening not in floating point

  • space but in arbitrary number precision space. So that’s a very accurate reciprocal. And

  • that kind of stuff is nice too, because you don’t see cache and conversions and worries

  • about overflows and underflows. Constants just take the job for you. And then we have

  • values, obviously. There’s an array like type called the slice. Those are arrays but

  • theyre kind of peculiar. You don’t use them much. Instead, use a reference type called

  • the slice. So we can there, is declared to be a slice of strings with Saturday and Sunday

  • as strings declared inside it. And then we take the timeZones and make declare timeZones

  • map to be a map from a string to TZ or timeZone. And you can see how that works. It’s pretty

  • straightforward. There’s a function declaration to do an "add." You can see the function syntax

  • there. There’s actually a lot of interesting things in how functions deal with return values,

  • which I’m not going to talk about today, but you should check that out. And then, there’s

  • a declaration of function type which takes two integers return int, so "add" is of type

  • Op. And then, here we declare an RPC, which is a structure. I showed that before but it's

  • a [INDISTINCT] example. It’s got A and B integers. It’s got an operator, and it’s

  • got a result which is a pointer to an integer. And all that should be fairly straightforward

  • even if the declarations look backwards to a C programmer. And then the last line there,

  • we declare using a structure literal, an instance of an RPC and again, it’s very simple. You

  • just say type name, open brace, list the elements of the structure, closing brace and then you

  • got a value, you can assign that to or in this case, initialize a new variable to that

  • value. So, I said [INDISTINCT] language. We haven’t seen much yet, there was actually

  • one and the other is a method in the echo example where we wrote the os.Stdout. But

  • let’s talk about methods, because theyre kind of different. So here’s a type called

  • point that has X and Y. Now, those are upper case and the reason is, in Go, the complete

  • decision about whether an identifier is visible outside the package or not, is whether or

  • not it starts with an uppercase Unicode letter. That’s it. So if a variable or a type or

  • whatever declared at the top level is uppercase, is visible to the clients of the package.

  • If it’s lower case, it’s not. Inside the global struct, if a method or field is uppercase,

  • it’s visible to the clients of the package, otherwise, it’s not. That’s it. It’s

  • really simple. So, there’s that type. Now, were going to define a couple of methods

  • on it. The declaration syntax for a method, youll notice it’s not declared inside

  • the struct, and the reason, we'll see in a minute, is a method and structs are independent

  • ideas. You can have methods on things other than structs, so it wouldn’t make sense

  • if you put them inside the struct declaration. What you do is you say, "Here’s a func."

  • And then before the name of the method, you write a parenthesis, kind of like its own

  • little one element parameter list, receive a declaration and receiver is a short hand

  • for the thing that’s receiving the method when it’s called. So this says, that scale

  • is a method of type star point and it takes a float argument and then the implementation

  • is inside and it’s just multiplies up the point by the usual, by the scale factor. Youll

  • notice that the receiver is explicit. There’s no this, automatic or anything like that.

  • You have to actually say, declare receiver and use it if you need to access the fields

  • of the struct inside the method. And then there’s Abs, you can imagine what that is.

  • There’s a square root, which is a function inside the math package computing the hypotenuse

  • of the point of the [INDISTINCT] of the vector. And then here’s--we declare an X. Now, this

  • time you notice there’s an ampersand before the point, word there. Point of three, four

  • is a value. Ampersand of point of three, four allocates. It’s like a constructor like

  • thing to create a pointer to a new instance of that. And that--every time you execute

  • that, you get a new instance of point that initializes the three, four. Then, you can

  • call x.Scale, which is assumed you'd expect to be able to do. Okay. So that’s pretty

  • simple. The syntax is slightly different, but the ideas are pretty simple. Now, it gets

  • more interesting because methods on any type you define. And here’s a full example, this

  • is another complete program that actually does something a little different. So again,

  • we start with package main and now we import fmt, which is the formative printing package.

  • It has printf and stuff like that in it. And then, here’s our type TZ int coming back.

  • And now, we declare few more of these constants, we have an Hour which is of type TZ, which

  • is 60 minutes times 60 seconds. And then we declared, just to make it short, two timeZones:

  • Zero hours and minus five hours for UTZ and EST, okay? Now, we declare a map from the

  • names to the values of those timeZones. That should be familiar in the timeZones. We actually

  • have that exact the same example before. And now, we put a method on a timeZone. Now, timeZone

  • is just an int, but I’m going to put a method on it. So, I declare a function called capital

  • string that returns a string to receive tz, lower case, plus a type TZ, upper case. Notice

  • that it’s not a pointer, that’s really important. It doesn’t have to be a pointer.

  • And then, using a variant of the for-loop that's arranged over the elements of a collection,

  • I say name comma zone is range of timeZones. What I’m looking for is the element of the

  • timeZone map whose value is equal to the value of TZ. That’s the name of the guy I want.

  • So it’s like reversing the map. So I just loop over all the elements looking for the

  • one whose timeZone is equal to the zone of that element of the map and if that’s true

  • I return the name. And you can see there’s actually quite a bit going on in there. There’s

  • the range which is giving you the iterator, there’s a cone [PH] equals to declare loop

  • variables that work over the elements and thing inside in and all not. But of course

  • you might get a value of the--of TZ integer that’s not an exact timeZone number. And

  • so, if that happens, we finish the loop and we return fmt.Sprintf of blah-blah. An Sprintf

  • is analogous to the standard C as printf, but actually returns a new string. It doesn’t

  • put into a buffer. So, that’s an implementation of a method that let’s you print timeZones

  • in interesting ways. So we can use it in our main function by saying, if we just say, fmt.Println

  • of EST, Println is a variant of print that doesn’t require a format. Itll work.

  • Itll actually printout EST by catching it in the inner loop of the string method.

  • And notice that Println(EST) knows under the covers by mechanisms that are described the

  • length and the website, how that the timeZone type has a string method and that’s how

  • you should pretty print it if you get a value of that type. So, that’s all you need to

  • do to make it print itself. And then, there’s another example, we can print Println five

  • times hour over two and it comes out as plus two colon thirty, because the printf at the

  • bottom works. So this is a fairly contrive example, but you can see to there’s a [INDISTINCT]

  • going on here. Having methods on general types, as any small talk programmer will know, a

  • very convenient thing to do. But by separating them methods away from structural classes,

  • we actually introduce some new ideas that you can play with and that’s pretty fun.

  • Okay. So now, we come to something that I will not be able to describe in full in the

  • time available, but they are pretty interesting and they are arguably the most noble about

  • Go, and that is the concept of an Interface. An Interface is an, what’s the word, a formalization

  • of the concept of a set of methods. So, we can declare a method, sorry, an interface

  • type Magnitude and say that anything that implements the Magnitude interface is something

  • that implements the Abs method that returns a float. And of course there could be lots

  • of other things in there, but well assume for the moment there’s just one. So, remember

  • we declared an Abs method for the type star point. So, we can--we had an x from the previous

  • slide, we go back there, there, that x address the point three, four, that’s the same x.

  • We can use it here. We declare a variable with the interface type magnitude and assign

  • it to assign to it the value x. And the reason we can do that is x is an implementation of

  • that interface, and so that’s a valid assignment, okay? And having done that, had I typed var

  • m magnitude instead of m magnitude. No, I got it right. Sorry, sorry, I confused myself.

  • Var m magnitude is a variable, we assign to x and then we declare a new variable mag that’s

  • m.Abs, so it’s just the, the vector length of the point x. But now we declare another

  • type point three which has three coordinates to find the Abs method for that, same idea.

  • And now, we can assign m equal to a point three and that value still is an interface

  • var, but inside it is an object that has the implementation of the Abs method. And so we

  • can call the Abs method on that and add that to the variable that weve got. And then

  • we can do it again, and this time just to be fun, we declare a polar object, which is

  • R and theta and, of course, that’s a capital theta because a public field. And then, we

  • declare p Polar. Notice there is not a pointer this time. Why make it a pointer, it doesn’t

  • matter. So we just make it a value polar and it returns the radius of the thing which is

  • the definition of the magnitude. And then we design a value that type to m, and now

  • we can add another thing at the magnitude. So the interface variable is letting you define,

  • "I can work with anything that implements these methods and anything at all will do."

  • Here, I use three different representations of a coordinate, but theyre quite different

  • in character. Under the covers, it’s all very simple. And the key point is that nowhere

  • does point three or polar have to tell you that it implements the magnitude interface.

  • It implemented the fact, though, because it satisfies the methods that are defined by

  • the interface. And there’s way more going on there than I have time to talk about, but

  • I have to talk about one and very important concept behind them, which is the generality

  • that they give you, because any method, it could be part of an interface, an interface

  • can be any method. It's all sort of, it’s not one to one, it’s many to many. It’s

  • all mixed up. And so a struct of a given type may implement multiple interfaces depending

  • on what interface you are using. And that gives you the opportunity to define very simple

  • interfaces that define very general properties. And a really good example of this is in the

  • IO package and it is called the Writer interface. And a Writer is anything that implements a

  • standard write call and that’s what we define a standard write call to be. The, you know,

  • there’s a slice of bytes that can--that is the data youre going to write. It has

  • a length inclusively inside it, so we don’t need a byte count. And it returns, there’s

  • that function that [INDISTINCT] before returns a pair, a count and an error, but don’t

  • worry about that. Just think about the writer. The writer said anything that implements this

  • standard form of the write call can be used to write it to. It makes sense. This is just--it's

  • almost a tautology. But now, anything you implement write for can be used by anybody

  • that only needs something that implements write. It doesn’t matter where the properties

  • it has. So for instance, fmt.Printf which is just what it sounds, fmt.Fprintf, pardon

  • me, which is product much what it sounds like, doesn’t take a file as the first argument.

  • It takes an io.Writer as its first argument. And a result, you can call fmt.Fprintf on

  • a network connection, a pipe, a file descriptor, a buffer, all kinds of other things, anything

  • that implements write, a cryptography pipeline. And then, the way buffer io is done in Go

  • is that there is no such thing as buffer io, there’s just buffering. And what happens

  • is if you want to create a buffered version of something, you give it a writer which is

  • anything that implements write into the covers and it gives you back a buffered version of

  • that same thing that you can use where you used it before. So here’s an example that

  • puts that together, again, a complete program. Starting with package main, we import bufio,

  • fmt and os again. And now, we wrote the os.Stdout before, but now were going to use Fprintf

  • to write to it to make it explicit. So, we say, fmt.Fprnintf os.Stdout hello. Then, we

  • call bufio.NewWriter. We pass it os.Stdout but NewWriter only--all it cares about os.Stdout

  • is that it implements the right call. And the NewWriter function inside bufio returns

  • something else that implements the writer interface, and so I can write to it. So, I

  • can call fmt.Fprintf of buf and now I have a buffered write. So I better flush it when

  • I’m done. But you see the Fprintf use two different types in there for its output and

  • it worked, because underneath--if you look at the Fprintf declaration, all it cares about

  • is that the thing that is being passed in implements the write call, which of course

  • they do and it’s type checks, so you know they do. So, there's a lot more of that stuff

  • to talk about to, but were trying to skip through the highlights. Communication channels

  • are little as radical than Interfaces because theyre based on, worked on in some early

  • language, going back to a Hoare’s CSP. But unlike Hoare’s original CSP, the communication

  • is done through first-class values called Channels. His second round of it done about

  • 10 years later had these, but we’d played with them linguistically by then. And, the

  • ideas, you make a Channel, it has type string. That means you can send and receive strings

  • on that channel. Just like a pipe that you can send type values through. And so, that

  • notation with the left facing out is the communication operator when you used infix it means send.

  • So, that sends the string, hello, down the channel. And somewhere else, some other time,

  • some other Goroutine can do read from channel c by doing a prefix operator on c of that

  • communications and get out the greetings, so it will see greeting as assigned to hello.

  • And this is haven’t done giving Goroutine because the channel is synchronized by default,

  • hello. You can control that when you allocate them. And one of the cool things about having

  • them is you can make them--channels can actually be first class size. That means you can pass

  • a channel on a channel. And I’ll show you in a minute to actually give you some interesting

  • capability. So, if you have someone else wants to have this channel that you can send greetings

  • on, you can pass it to him over channel then he can send you greetings, all right? So,

  • to do that, though, we have to talk a little bit about Goroutines. So, I’ve mentioned

  • some calculations, it just takes far too long, right? Who wants to wait around for that?

  • You're going to block forever waiting for the calculation, but maybe you don’t want

  • to. What you can do instead is create a channel to get the answer back on. And then declare

  • a function, wrapper, that takes the value of the parameter for the calculation, and

  • a channel invokes the calculation and then when it is done, sends the result back. And

  • I broke it in two lines just to make it easier to read. You'd probably just write C gets

  • long calculation of A in a real code, okay? And then, to run the thing, there’s a Go

  • keyword. Go is a keyword. Go wrapper of 17c says, "Take the function call, 17 comma C,

  • and run in the background and let me keep going." Okay? And then, eventually, you want

  • to hear what happened, so once youre finished doing your business, you come back and say,

  • "Okay, I’m ready for the answer now." And you say, "Now, I want to receive from C and

  • get the result." So I’ve taken this calculation and I’ve solved it off over here and then

  • it slows back to me by doing a receive on the channel down underneath. That should be

  • fairly easy to follow. This might not be so easy, but well try. This is a multiplexed

  • server. At least, the server side of it, I’ll show you the client on the next slide. And

  • the idea here, remember I said you can pass a channel to a channel. What we have is a

  • request which is a request for the server to implement. That's trivial. It just takes

  • a pair of integers in the channel in which it replies. Very much like what we did before

  • on previous slides, generalized somewhat. We defined a binary operator type and we defined

  • a function run that takes a binary operator and a request and sends on the reply channel

  • inside the request the value of running the operator on the arguments inside the request.

  • So that’s just turning to send the operations in the sending of the thing from the previous

  • slide into a function, not very exciting yet. But then, we defined a server function that

  • takes an operator that is going to serve in a channel of request. And it’s just sits

  • in a loop reading request from the service channel and then saying run of Op request,

  • but it puts a Go keyword at the beginning. So, it runs all these requests in parallel

  • in the background. The server is never blocked. It’s always ready to receive another call

  • no matter how much is going on. Obviously, there's issues about re-limiting and stuff

  • like that, but let's not worry about those. The key point is that that’s, basically,

  • a server loop. And then, to make it easy to use for the client we defined a public function

  • or an exported function by starting with a capital letter, starts server. And it says,

  • "Take an operator and start a server for that operator and return the channel on which those

  • requests can be sent. So, what we do is we allocate the channel, a channel start a request,

  • we start the server process which in turn is going to start the little implementers

  • of the operator as they come in. And then, we return the channel as the return value

  • from start server. So, you call a function you get a channel back, now you got a thing

  • you can talk to and that is the fundamental idea on how you use this stuff to build services,

  • okay? So on the client side, it looks like this. You say, server, start server, here's

  • a function. Now, notice that I’m just writing a function in line there. Go has four closure,

  • it seems writing down its expressions. And so, now I’ve got a server running that’s

  • going to add numbers for me. And I’ve got a channel for that server in the variable

  • server called Lowercase Server. I allocated a couple of request in the obvious way and

  • inside the request, I allocate new channels because I want to do--respond to me on separate

  • channels for whatever reason, okay? And then, I can send the request to the server, it doesn’t

  • matter what order I send them. It’s totally not blocking. I'll just send them anywhere

  • I want. And now, I can print them out again, print the results as they come back. And I

  • don’t have to worry about the order because, again, it’s totally parallel. So, in fact,

  • I send one first but ask her two first. And if two takes forever, I’ll still hang around

  • there waiting for the response to come back and once it finally does then I’ll print

  • the value on one even if one is ready sooner. So, this one is very rushed through hear,

  • so I apologize if I left you a little be fuddled, but there’s examples like this in the tutorial

  • and some other documents. It should make a little clear what’s going on if that looses

  • you. Now, if we go back to the server here, remember I said, it has a rate limiting issue

  • and also the problem is it runs forever. You want to go and shut it down. One way to do

  • that is to use a control structure in Go called the Select, which is quite a rich control

  • structure. But the basic idea is given a set of communications on channels. Select let’s

  • you choose, let's you to actually wait for any one of them to be become ready and once

  • it does become ready, let that single thing communicate. So, it’s like a switch statement

  • for communication. So, if we replace the inner loop of server, which was just, remember,

  • get a request and then run Go on it. With an operator that has a select statement inside

  • it and the second channel called Quit, that’s passed into the server when we create it.

  • Then, we can just run this normally. It will just do what it was doing before, but as soon

  • as you want it to go away, we just send a signal by sending a Boolean of any value,

  • it doesn’t matter what, on the Quit channel and that branch of the select will fire and

  • this function will return, which is equivalent to exiting the Go routine. So, that’s again

  • pretty quick and I apologize for that. But I want to make sure we hit some of those points.

  • And in fact, there’s a lot more to talk about. I haven’t talk much about package

  • construction. Initialization is actually quite interesting in Go. It's much--it's sort of

  • hard to see, but it does a lot for you. It can help you set up things like RPC servers

  • with almost no code and stuff like that. There’s fall reflection, you can reflect from there,

  • you can reflect on functions, channels, maps, all kinds of stuff. It’s got interesting

  • some dynamic typing going on if you wanted to, but you don’t have to use it. There’s

  • a thing called Embedding that is a little bit like an inheritance, but somewhat more

  • simple and yet general. There’s iterators that come out of the way. The range thing

  • works on fours in our channel’s functions, things like that. And there’s some interesting

  • testing software, but I don’t have time to talk about any of these right here, but

  • I just want to make it clear there’s a lot more of the language than what I have time

  • to show you. So let me close this section with another interesting example. This is

  • a real communications example. Remember, we started this language because we want to build

  • servers. And one of the problems with building servers in the modern world is there’s this

  • model of a thread per request, which is quite labor intensive and resource intensive to

  • run and quite difficult to get right in more languages. And we want to make it easy to

  • think about having tens of thousands or even hundreds of thousands of threads—-whatever

  • they are-—working on your behalf. And to prove that we got some way towards that. This

  • is an example that will create a hundred thousand goroutines and then they can do something.

  • And what it does, you probably won’t be able to decode this in real time, but what

  • it does is it has a little function F there that all it does is read a value from a channel,

  • add one to it and send it out again. So, there left gets one plus, get from right. It’s

  • that thing inside F. It just passes its token along but adds one to it, okay? And inside

  • main, we declare the left most piece—-to go your direction—-and then a couple of

  • variables. And then for the number of goroutines you want to start, we sort of thread a new

  • piece on and walk away along, but we remember where we started. So, we stitch together a

  • bunch of goroutines like this, each of which is passing a channel value along to the next

  • one. And so, we end up constructing, in this case, a hundred thousand goroutines off turning

  • together like pearls on a string. And each end is waiting for the guy upstream to give

  • him a value. So, then right at the bottom there after the loop--once we built this thing—-we

  • say, drop a value into the right hand side and it goes pfft and pops out the left. And

  • the value that comes out is of course the number of goroutines in the chain because

  • weve added one for each step, okay? So, you can examine that later if it confuses

  • you, but let me show it to you actually running. Okay. So--oh dear, I think it was the wrong

  • file—-okay, sorry it took so long. And now, I’ll run it—-now remember this is a little,

  • a little mac air very fast. That's a hundred thousand threads of control--I won’t say

  • threads because that’s not how it is done—-but just incase youre wondering, it takes about

  • 1.5 seconds to manage a hundred thousand goroutines. And it’s real--it’s honest to God management

  • too. It’s [INDISTINCT], it’s stitch together communication. Doing the communication and

  • it’s tearing them down. This hasn't created an instant kill, this is a legal honest build,

  • use them, tear them down. It’s kind of a minimum thing you can do that, but still,

  • hundred thousand is an interesting number and we could go more but it start to use up

  • memory. So, let’s just prove that there’s—-anyone knew that. Here we go. So, that’s concurrency

  • showing that you are going to at least, conceptually, have many, many things. Now, the goroutine

  • implementation has to worry about real threading and real stuff like that when youre doing

  • I/O operations that could block but that is taken care off. So, you are left with a simple

  • mind example, it’s indicative of something that really works. So, let me talk a little

  • bit about the status. It’s actually quite a bit to say, we have two complete implementations

  • in two different compiler technologies. Ken Thompson wrote a suite loosely based on some

  • of the Plan 9 tools but it’s from scratch, and using the peculiar notation, 6g is the

  • AMD—-it’s a 64 bit X86 compiler. There’s also a 3D 61 and an ARM which is five for

  • reasons. Don’t even ask. But anyway, the point is there is a compiler. That’s the

  • one I’ve been using today. Some are more experimental than the other compiler but as

  • youve seen it, it generates code quickly. The code it generates is pretty good, it’s

  • not as good as what comes out of GCC, but it’s better than you might think for a compiler

  • that goes that fast. But, in order to do that, it got it’s own rules and so, the output

  • is not linkable directly with GCC. But there is a foreign function interface support that

  • is coming along pretty well. We can call C-code from Go with this compiler just fine and once

  • we get Swig work and were able to call C++ code. And then Ian Taylor, wrote a GCC

  • front end for Go which is a complete implementation--I should say, by the way, that Ken’s compiler

  • is written in C for bootstrapping reasons, although, honestly it would be a great language

  • to write a compiler but it’s written in C for now. And Ian Taylor thing is a C++ front

  • end for the GCC backend. It generates excellent code with GCC quality but it’s not as fast

  • it’s about something like four or five times slower. But the real advantage of compiling

  • GO isn’t the compiler speed, it’s the compilation speed. The whole picture is where

  • the speed really comes from. And both these compilers supports 32 and 64 bit x86 and with

  • ARM compiler that Kyle has been working on that’s almost ready—-I think it’s up

  • to 97% to test suite compliance now. So, we are very close. We have to have it ready in

  • time for the open source release. And for performance of the generated code, it varies

  • obviously because it’s different but if you avoid some of the libraries for which

  • have weak implementations. Typical inter loop kind of performance or standard programming

  • gets you typically to 10 to 20% range with the GCC tending to be more like—-by which

  • I mean 10 percent slower than C and Ken’s compiler is typically like 20% slower. So,

  • 1.1x to 1.2x, but this is for a type save, statistically compiled garbage collection

  • language. It’s pretty nice. And I’m happy to give up 10 percent even with words lost

  • flowing down, that’s still not very much clock time on the calendar. So, there’s

  • a Run-time that handles all the memory allocation, garbage collection, stuff like that, the stack

  • handling stuff which is pretty special but very important. The goroutines support channels,

  • slices, map, reflection; all of that stuff is built into a real run-time. So, even though

  • it’s a system language it has a really powerful run-time system including dynamic type reflection.

  • And it’s pretty solid. It’s improving, it got ways to go especially in memory allocation

  • and some of the scheduling stuff, but that’s yet to come, but were working on it. 6g

  • has a very good goroutines support and much of them on the threads well and implements

  • what we call segmented stacks, which is how we keep the footprints small but let them

  • grow as they need to. GCC goes a little behind on that because Ian has been working on a

  • few other things lately. But we hope by the end of the year to have all that stuff working

  • in GCC Go and theyll basically be at the same stage at that point. But even so, GCC

  • Go can compile all the code and run it now. The garbage collector, 6g has a simple but

  • effective mark-and-sweep collector. And this sounds simple, but work is under the way to

  • do a much better job. We believe, with multi-card machines, you can actually do concurrent garbage

  • collection with essentially zero latency and very little cost and overhead. And IBM has

  • this garbage collector technology that we think is pretty exciting. We think building

  • on that stuff, we can actually make our real goals which are to avoid a lot of the pitfalls

  • that garbage collector tend to have. And weve done work in other languages before that indicate

  • this really can be done and now that we have multi-card machines we believe that we can

  • really solve it. GCC Go at the moment has no collector, but, as I said, we're working

  • on a common run-time, and I hope by the time this collector is done is design to run with

  • either compiler. It’s part of the general run-time so both compilers will have real

  • garbage collectors inside of them. There’s lot of libraries, there’s tons more to do,

  • but we have a pretty good start. Weve got obviously, OS and I/O stuff. I showed you

  • some of that. It’s got a nice math, a simple math package. It got strings, good support

  • for Unicode, rudimentary but functional regular expression implementation. It’s got run-time

  • reflection, command-line flags and logging, which are very nice to use. It's got full

  • hashes and crypto and all that kind of stuff. It's got a really good testing tool and a

  • library to support it, standard networking libraries just like you’d expect, including

  • a native RPC implementations. It’s kind of pretty. There’s a really interesting

  • template library based on some work that Andy Chu did that let’s you write HTML or, in

  • fact, anything at all using this to generate really simple data driven page generation.

  • It's really quite nice. Andy gets most of the credit for that. There’s a lot more,

  • but you can see there’s actually quite a bit in place already. So, one of the most

  • interesting programs written in Go is a pair of things that are related--they share a lot

  • of code--called Godoc and Gofmt. Godoc is analogous to Javadoc. It serves documents

  • to request to look up, you know, what this package does or what that function does. And

  • there’s a set of links listed there. Golang.org is a top-level guide that’s running Godoc.

  • It serves the landing page. And underneath that, you can find all the other documents

  • specifications, editorials, and FAQs, and stuff like that. But if you dig down into

  • the package subdirectory, that’s really interesting, automatically generate the package

  • documentation is especially quite rich. And then under the source directory, the source

  • gets served, but, of course, you can get out of this code repository, too. The difference

  • is that the source is processed by the coding Gofmt. The Gofmt is a pretty printer and all

  • of the coding repository has been formatted by Gofmt. So, rather than set a bunch of style

  • rules, we have a program that says this is what a code looks like, and you just run through

  • Gofmt when you check it in and that’s, just settles all those arguments. If you want debate,

  • if you wanted debate, we got to debate by changing Gofmt. You can’t debate by changing

  • a document, and I think it’s actually, it does an amazingly good job. Actually, Robert

  • [INDISTINCT] a good job. We have a debugger. It’s not quite ready, but it’s pretty

  • close. I hope by the end of the year we'll something functional but well be happy

  • to show. But it's coming along and it will work with either environment but at the moment

  • its working in the 6G world primarily. Gccgo users can of course use gdb. Gdb doesn’t

  • understand the symbols tables. They're coming out of Ken's compiler, so it doesn’t work

  • very well with that. But with Gccgo compilation, you can use gdb, but it thinks that the C

  • program is debugging and there’s some weirdness in the symbol table. And also it doesn’t

  • know anything about the run time, which is a critical thing when youre debugging on

  • an environment like this. So, we really got to get our debug up to scratch. We had a summary

  • in turn. Austin Clement was here working on that. It's pretty close, but not quite ready

  • for real use. One question everybody wants to know is what about generics. And the answer

  • is Go doesn’t have them yet. We don’t understand exactly what they do in Go’s

  • world. Theyre quite subtle. The easy examples are easy to write down. It's obvious what

  • the easy examples do, but the complete, correct definition is going to be quite complicated.

  • We want to make sure we get it right. In some ways, Go makes it simpler because there’s

  • no type inheritance, and that eliminates one branch of complexity in generics. But on the

  • other hand, you can put methods on things that are values of arbitrary size, so, that’s

  • a consequence, and the other directions are complicates and simplifies at the same time.

  • And we just don’t think we understand it well enough to do them yet. Also, in the current

  • world, although that would be definitely useful and could solve a lot of problems, the map

  • and slice implementations and the interfaces themselves actually cover a lot of the sort

  • of obvious examples for generics, which is not to say they wouldn’t cover a lot of

  • others if they came along, but the need isn’t quite as acute as it is in the language. It

  • doesn’t have those features. You can in fact build collections fairly nicely using

  • what’s called the MT interface, which is just interface open close. That’s an interface

  • that implements no methods because everything in the world satisfies the MT interface. It's

  • kind of a little bit like it but in a completely different meaning the object in Java. And

  • you can build collections that use. There's quite a few checked in, but they have the

  • disadvantage that theyre not type safe since you have to unbox manually and stuff

  • like that. Theyre not really what we would propose to do instead. It's just what were

  • using for now, why we struggle at this question. So generics, not yet but they're very subtle.

  • It’s interesting in the codes workbook, Josh Black has a long discussion about them.

  • And I think most people think that Java generics works really well including Josh, but he points

  • out they're actually quite a bit harder to get right than you think, and then maybe it's

  • time to think really hard before you put them in. So, they may come but they're not there

  • now. And, of course, there’s a million of other thing. Where’s my feature? Everybody

  • who programs has a feature they want, and chances are that some of the things you really

  • think are important are missing, or they might be there but not in the way youre used

  • to. A really good example is inum but there is no iota. And iota's an interesting thing,

  • but it's not an inum. It's different. So, it may not be there, but there may be some

  • way to do what you want. It’s just Go is different or almost as good or maybe even

  • better. But why is it a feature there? Well, maybe it doesn’t really work in the language,

  • you know. Like there’s no point of arithmetic, point of arithmetic is nice but we can’t

  • do a point of arithmetic and make a language safe, there just not there. And the compiler

  • makes up for trying to compile a way some of the inefficiencies you get by having your

  • index and everywhere but on the other hand you got a safe length. So, a lot of the things

  • the people expect the language like this were not there because they break the rules and

  • we don’t have them. Or at least they break principles about what we think for language

  • should do. And there’s also a possible--like generics is a good example. They're just not

  • on top of our list. It doesn’t mean it won’t happen. Union types is another one weve

  • been thinking about. Actually, I think it would be a very good proposal for them, but

  • we haven’t done that yet. So it’s possible some of the things youre finding for will

  • actually occur fairly sooner or not too far out. But it’s a different off language that

  • even if it doesn’t have the features you want, it may have features you haven’t used

  • before, if I can guarantee that some of you haven’t used before, the interface stuff

  • is very interesting. And don’t let the lack of things you expect stop you from playing

  • with things that are there and seeing that it does actually do of some pretty interesting

  • stuff. And a lot more information on this topic available is actually explicit language-assigned

  • FAQ on the website and it talks about a lot of the "why things aren’t there" things.

  • So, to conclude, I think we really have a nice language. I’m having more fun programming

  • than I’ve had in a long time because I feel like I’m getting work done, because I’m

  • getting work done. It’s early yet. I think the language is going to evolve some more,

  • these things we know, but a lot of the basics are locked down pretty well. I feel pretty

  • comfortable with them. It’s a very comfortable language to work in. It’s very productive.

  • You can write code really fast and have it work and be safe. There’s tons of documentation.

  • There’s a specification, complete spec of the language. There’s simple to trial for

  • beginners. There’s a document called Effective Go, which is growing to sort of explain idioms

  • and how you think about things and language differently. There’s some FAQ, and there's

  • even other things than that. All the implementations are available as open-source, the 6GHG5G suite

  • and all its tools, the gzgo and all that stuff is also in the different place, but it’s

  • also going out and it will be linked from the landing page. And so, if you want to try

  • it, go get it. If you want to help, please do it. There’s tons of work to do to build

  • it up to another level. We really are welcoming people to come in and talk about stuff, especially

  • if they want to help us do some interesting library work or build new tools, there’s

  • plenty of room for things to happen. So that’s our site and that’s our language. Thanks

  • for listening.

>> PIKE: I’m going to talk about the Go Programming Language, which is going to be--we

字幕與單字

單字即點即查 點擊單字可以查詢單字解釋

B1 中級

Go編程語言 (The Go Programming Language)

  • 138 10
    Hhart Budha 發佈於 2021 年 01 月 14 日
影片單字