I’ve seen articles about Go programming language appearing on Hacker News a few times but I didn’t pay much attention to them. Yet another language with nothing special about it or so it looked. It’s changed with Rob Pike’s recent talk.

I decided to try it out in a simple program that I originally wrote in Python. The program takes CSV files with data about Japanese population fetched from official sites and produces a template for Russian Wikipedia. The program also uses an INI-like configuration file. You can see the original source here. It’s fairly straightforward, the only thing I had to do is to make CSV reader handle UTF-8 files by introducing unicode_csv_reader function.

I wanted the same functionality in a Go program. Reading CSV files seemed the easiest task to me so I started with it. Go standard library has a package to deal with such files, it’s called encoding/csv. Here is an example of how to use it:

file, err := os.Open("example.csv")
if err != nil {
	log.Fatalln("Error:", err)
}
defer file.Close()
reader := csv.NewReader(file)
for {
	record, err := reader.Read()
	if err == io.EOF {
		break
	} else if err != nil {
		log.Fatalln("Error:", err)
	}
	fmt.Println(record)
}

We open the file, command Go to close it when noone uses it anymore, create a csv.Reader object then read and print records line by line until we encounter end of file. Things to note: Go functions can return multiple values; you can defer execution of a function until the end of the block; Go has basic type inference (for example, reader := csv.NewReader(file) is a shortcut for var reader csv.Reader = csv.NewReader(file)). Go doesn’t have exceptions and it’s common idiom to return errors alongside function values. It makes code somewhat more verbose but it also makes clear when error will be handled.

The next stop was to read an INI-like configuration file. The standard library doesn’t have a package to read them but it was really easy to implement one myself. I took encoding/csv package source code and created my own package based on it. You can look at the result here: go-config at GitHub. Later I found out there are three third-party packages that do the same but all of them introduce Python’s ConfigParser API that doesn’t suit Go very well, in my opinion.

It was indeed fun, easy and straightforward as Rob’d claimed in his talk. Go promotes writing, documenting, testing and sharing packages: it has tools to automatically reformat your source code (go fmt), builtin testing library (testing package and go test), document extraction (go doc) and even to get, build and install third-party packages (go get) out of the box.

With all pieces in place I’d finished the program and it’s almost as easy to read it as Python version.