Recent Articles

Building Gophercises

This is a write-up of a talk I gave at the Gotham Go conference in 2018. It won’t be identical to the talk, but should cover the same topics and convey the same message. Whenever the videos from the conference are posted online I’ll also link to it from here. Slides from this talk can be found here. What is Gophercises? Gophercises is a free course I created that is composed of mini-exercises to help budding Gophers (Go developers) practice writing Go code and gain familiarity with different aspects of the language.

JSON APIs Are Just Web Applications

A common misconception is that a JSON API is vastly different from a web application that renders server-side HTML. In this article we explore how to convert an HTML-based web app into a JSON API in order to demonstrate how similar the two really are in a well designed app.

Why Cant I Pass This Function as an Http Handler?!

An incredibly common question I get when helping people learn web development is, "Why can’t I pass this handler function into a function that expects an http.Handler?" It is a logical question. The compiler can automatically convert those functions into the http.HandlerFunc type, so why can't it take the next step and infer that it also implements the Handler interface? Learn why (and more) in this article!

Gotham Go 2018

Slides from my talk at GothamGo 2018

Jon on the Go Time Podcast!

I was lucky enough to be invited onto the popular Go Time to discuss things like Gophercises, experiencing the joy programming, and more. If you want to check it out you can use the widget below to listen, visit the website ( to download an MP3, and lastly you can probably find the episodes anywhere else you typically consume podcasts (I have only verified Go Time is on Google Music and Apple Music).

Go Experience Report: Interfaces with Methods that Return Themselves

I want to describe a scenario where there currently isn’t a good solution in Go (at least that I am aware of). Let’s say you have something like the template.Template type with methods like Template.Funcs: type Template struct { *parse.Tree // contains filtered or unexported fields } func (t *Template) Funcs(funcMap FuncMap) *Template If we wanted to use an interface for this type, it is impossible to express in Go now.

Popular Articles

6 Tips for Using Strings in Go

Learn how to perform common operations with strings in Go. This article discusses how to write multiline strings, concatenate strings efficiently, convert various data types into strings, checking for prefixes, and converting strings to byte slices.

Using Functions Inside Go Templates

Go's template package provides many useful built-in functions. Learn to use a few of the more common ones, as well as how to add custom fucntions to your templates so that you can add any functionality you need.

Connecting to a PostgreSQL database with Go's database/sql package

This tutorial explains how to connect to a Postgres DB using the database/sql and lib/pq packages. It also covers potential errors and solutions.

Creating Random Strings in Go

A tutorial explaining how to create a custom rand package with functions for creating random strings of varying length with custom of preset character sets.

Inserting records into a PostgreSQL database with Go's database/sql package

Learn to insert new records into a Postgres database using Go's database/sql package, along with how to get the resulting ID of newly created records.

How to use slice capacity and length in Go

Learn about the difference between capacity and length and how to properly utilize them to make your Go code faster, cleaner, and memory efficient.

↓ Or check out some of my longer series. ↓

Each series covers a broader topic and is composed of several articles

Using PostgreSQL with Go

PostgreSQL is an open source relational database system that has been around for well over a decade and has proven to be a great all around storage choice when developing a web application.

In this series we are going to walk through everything from first installing PostgreSQL 9.5 all the way to using it with a Go application. While this post will cover all of the basics required to get started using SQL with Golang, it is not a full course on SQL. It is instead intended to guide you by giving you enough information to be productive, while not overloading you with details that can be learned as you progress.

In this series we will cover topics like:

  • Installing PostgreSQL on various operating systems (Ubuntu Linux, Mac OS, etc)
  • Interacting with a PostgreSQL database using raw SQL. This includes querying, inserting, updating, and deleting records.
  • Interacting with a PostgreSQL database using the database/sql package provided by Go's standar library. Again, this includes querying, inserting, updating, and deleting records.
  • Using ORMs and other third party librarys to interact with SQL databases
Let's Learn Algorithms

Algorithms are a core component in a computer science education, and when taught properly they can help a developer improve his or her skills massively. In this series we will work to both understand how common computer algorithms work, as well as how to properly code each of them in Go.

By coding each algorithm as we learn it, you will develop the skills necessary to translate a conceptual idea into correct and efficient code. While many developers will know how to solve a problem set before them, oftentimes bugs and issues can stem from minor mistakes that algorithm practice can help remedy.

In addition to coding each algorithm we will also discuss how it works as well as the efficiency of each algorithm. That is, we will discuss how fast or slow the code will be based on the size of the input. This is important because in many real world situations you can opt for simpler - but slower - code if you know your inputs won't be too large. Alternatively, you could determine that the simpler solution won't work for your inputs and know that you will need to spend some extra time on a more efficient algorithm.

If you are relatively new to programmer, or simply don't have a formal computer science education, I invite you to check out these articles. You won't be disappointed!

Learn Web Development with Go!

Sign up for my mailing list and I'll send you a FREE sample from my course - Web Development with Go. The sample includes three chapters from the book, and over 2.5 hours of screencasts.

You will also receive notifications when I release new articles, along with other freebies that I only share with my mailing list.

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Articles and Tutorials by
Jon Calhoun

Jon Calhoun is a full stack web developer who also teaches about Go, web development, algorithms, and anything programming related. He also consults for other companies who have development needs. (If you need some development work done, get in touch!)

Jon is a co-founder of EasyPost, a shipping API that many fortune 500 companies use to power their shipping infrastructure, and prior to founding EasyPost he worked at google as a software engineer.

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