Go: The Good Parts

Go is an opinionated programming language initially developed by Google in 2007. It is a statically typed language with a simple syntax, resembling C or JavaScript. It features garbage collection, type safety and large standard library.

Go can be statically compiled into a single executable binary, which could target a large number of operating systems (from Linux and Windows to Plan 9) and processors (i386, amd64 and ARM).

In HappyPancake project we found that Golang was a good fit for developing event-driven backend services. Other contenders included Scala, C#, Haskell and Erlang.

Here is how code can look like in Golang:

func (m *ContactsModule) handleList(r *ApiRequest) ApiResponse {
    return NewObjectResponse(&ContactListModel{})
}

type ContactsModule struct{}

func (m *ContactsModule) Register(r Runtime) {
    r.HandleApi("GET", "/contacts", m.handleList)
}

Good parts

Concise and simple syntax, easy to get started with.
Good facilities for writing concurrent programs that share state by communicating (goroutines and channels).
Good ecosystem for developing backend servers, all major drivers and libraries are generally available.
Decent integration story with native code.
Lightweight development stack with major IDE-like features provided by command-line tools (and available in different editors).
Unified formatting style for the language, provided by gofmt.
Compilation is fast even with large projects.
Go supports all major OSes and CPU architectures.
Lightweight type system with interfaces "by example" and type embedding.

As a new language, Go attracts a lot of talent and interested developers. There are some interesting projects taking place in this ecosystem.

Opinionated parts

Golang is an opinionated language which started as an experiment. Some of its design decisions can take time to get used to. This especially applies to developers with a strong background in Object-Oriented Programming.

Yet, these opinionated decisions ultimately add to the strengths of the language.

Focused Packages

Golang ecosystem encourages separation of code into compact cohesive modules which do one thing and do it well: packages. It is common to have packages with only one or two files.

This way of structuring applications follows the Unix way of building software. It also aligns well with micro-services architecture.

This approach might feel foreign for people coming from ecosystems which favor larger modules (e.g. projects in .NET). Yet it leads to code that is more simple and reusable.

Type System

Type system in golang is an opinionated one. It includes following features:

Data types in form of structs (plain DTOs).
Embedding types in each other.
Functions and methods (functions with a receiver for dot syntax: response.Render()).
Implicit interfaces "by example" (types implement interfaces by providing methods with matching signatures).
Lack of generics.

Go is unique in the way methods, interfaces, and embedded types work together.

Not so good parts

You must set and tweak GOMAXPROCS variable for each program which needs parallel execution.
You can build web applications and native UIs with Golang, but ecosystem there is rather immature, if compared to the other platforms.
Ecosystem can be lacking in unexpected places. For example we had to deal with shortcoming of default SQL layer and patch PostgreSQL drivers.
Debugging golang code is neither easy nor reliable.
Golang has prominent explicit error handling style; if followed blindly, it can turn code into a spaghetti of error checks.
Golang stores all dependencies as folders in GOPATH, e.g. abdullin/chk. Having a single global workspace makes things tricky, when you need to work with multiple versions of a library.

This is the state of Golang at the moment of writing. Things will improve over time.

More Examples

This is an example of a simple web server in go. It maintains a list of accepted jobs, which are served for GET requests.

You can POST new jobs to the server. It will process them asynchronously, adding to the list.

We coded this example with Tom Janssens while working on Happy Pancake project. Neither of us had any prior knowledge of go.

package main

import (
    "fmt"
    "net/http"
)

var queue chan string
var joblist []string

func init() {
    queue = make(chan string, 10)
    joblist = make([]string, 0)
}

func handler(w http.ResponseWriter, r *http.Request) {
    switch r.Method {
    case "POST":
        val := r.PostFormValue("job")
        fmt.Fprintln(w, "VALUE: ", val)
        queue <- val
    case "GET":
        fmt.Fprintln(w, joblist)
    default:
        fmt.Fprintf(w, "Not supported")
    }
}
func projection() {
    for req := range queue {
        joblist = append(joblist, req)
    }
}
func main() {
    go projection()

    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

Summary

I think, Golang is a great language for building fast back-end servers or utilities that work across operating systems.

Ecosystem and tooling around golang are young. This attracts some talent but might create additional problems for certain projects.

References

Published: December 02, 2014.

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