First steps with Go

November 16, 2009

programming

I joined the go-nuts mailing list a few days ago and it really feels good to receive 200+ emails per day again. Just like in the good old days before good spam filtering (and anti-spam laws).

I also re-watched the presentation Rob Pike gave for Google Tech Talks on youtube.com. In there he presented the following program chain.go: (Formatted with gofmt as it should)

package main

import (
    "flag";
    "fmt";
)

var ngoroutine = flag.Int("n", 100000, "how may")

func f(left, right chan int)    { left <- 1+<-right }

func main() {
    flag.Parse();
    leftmost := make(chan int);

    var left, right chan int = nil, leftmost;
    for i := 0; i < *ngoroutine; i++ {
        left, right = right, make(chan int);
        go f(left, right);
    }
    right <- 0;             // bang!
    x := <-leftmost;        // wait for completion
    fmt.Println(x);         // 100000
}

In this short program we make a chain of 100000 goroutines which are connected to each other. Each one adds 1 to the value it gets from its right neighbor. We start it of by giving the last one (right) a value of 0. Then we wait until they are finished and print it.

Compile and run

To compile the above program you

8g chain.go 
8l -o chain chain.8

And then run it

./chain

On my crappy laptop this takes about 2.3 seconds. Not too bad :)

Vim For Go code editing, I’ve added the following to my ~/.vimrc

autocmd Filetype go set textwidth=0
autocmd Filetype go set noexpandtab
autocmd Filetype go set tabstop=8
autocmd Filetype go set shiftwidth=8
autocmd Filetype go set softtabstop=8
autocmd Filetype go set number
autocmd Filetype go command! Fmt %!gofmt

The last line adds a new command which reformats your Go code. Just do <ESC>:Fmt and you’ll end up with properly formatted Go code. The coding style rules for Go are simple. Its what you get when you run it through to gofmt.

Misc