Blog

Add a Little Safety to your Elixir Structs with TypedStruct

April 6, 2020

I’m working on an Elixir app at the moment and really enjoying it, but some of my recent dabbling in the type-safe worlds of <a href="https://elm-lang.org">Elm</a> and <a href="https://crystal-lang.org">Crystal</a> have left me desiring a bit more structure in my code. The app I’m building involves a multi-step data transformation and so I have a data structure to properly represent this process. But since Elixir is a dynamically typed language, you can’t, for example, have a non-nillable field in a struct. The Elixir/Erlang ecosystem does, however, have a type-checking syntax called <a href="https://hexdocs.pm/elixir/typespecs.html">Type Specs</a>, along with a tool, <a href="http://erlang.org/doc/man/dialyzer.html">Dialyzer</a>,...

#elixir #typespecs #vim #vscode

Upcoming Phoenix Authentication Solution

April 2, 2020

I’m in the middle of writing an application in <a href="https://elixir-lang.org">Elixir</a> and <a href="https://www.phoenixframework.org">Phoenix</a>, so when I saw a link to <a href="https://dashbit.co/blog/a-new-authentication-solution-for-phoenix">an article by José Valim</a> on an upcoming authentication solution for Phoenix, my initial reaction (before reading it) was negative. José is the author of the <a href="https://github.com/plataformatec/devise">Devise framework</a> for Ruby-on-Rails, so I assumed it was going to be the same idea, but for Elixir and Phoenix. I’ve implemented Devise in a handful of Rails apps, and each and every time I ended up ripping it out and writing my own auth solution (often based on <a href="http://railscasts.com/episodes/250-authentication-from-scratch-revised">this Railscasts tutorial</a>). The reason is that while...

JavaScript Sprinkles with AlpineJS

March 24, 2020

I’m a big of <a href="https://reactjs.org">ReactJS</a>, but sometimes it is way too heavy for what I need. The majority of the applications I create are server-rendered and just need some “sprinkles” of JavaScript. In the past, I’ve leaned on <a href="https://jquery.com">jQuery</a> for this, but I’m not a fan of the imperative nature of it. Recently, I stumbled upon AlpineJS, which is a super minimalist framework that lets you write declarative sprinkles of JavaScript without resorting to something heavier like React or <a href="https://vuejs.org">Vue</a>. It comes in at just 6.4kb (compressed), less than a quarter of the size of Vue, React, or jQuery...

#javascript #alpinejs

Enable Spell Checking in Vim for Markdown and Git Commit Messages

October 21, 2019

I had a ridiculous typo in a Git commit message recently, so I decided to explore spell checking in Vim. As it turns out, it’s extremely easy. I only wanted it enabled for Git commit messages and markdown, so I added the following to my vimrc / init.vim: <div class="highlight"><pre class="highlight viml"><code>" Spell-check Markdown files and Git Commit Messages autocmd FileType markdown setlocal spell autocmd FileType gitcommit setlocal spell </code></pre></div> By doing this, it highlights potential misspellings in red underline. You can see a list of potential corrections by moving the cursor over the word in normal mode and...

#vim #til

Dark Mode and other site updates

October 20, 2019

Inspired by iOS’s new dark mode (and halloween!), I decided to a dark mode to the website using the new <code>prefers-color-scheme</code> media query. It was surprisingly easy to do. After I’d changed the This took care of 90% of it: <div class="highlight"><pre class="highlight css"><code>@media (prefers-color-scheme: dark) { html { background-color: #19222b; color: #eee; } .page-wrapper__inner { background-color: #222f3b; color: #eee; } } </code></pre></div> Using a straight black-and-white background and foreground combo looks too harsh on the eyes, so you want to find a gray-ish background. Mine is a bluish-grayish...

#css #meta

Quickly Convert 4 Spaces (or Tabs) to 2 spaces in Vim

October 19, 2019

Here’s a handy Vim command that I find myself searching for often. It could easily be made into a function in your vimrc. <div class="highlight"><pre class="highlight viml"><code>" 4 spaces to 2 spaces %s;^\(\s\+\);\=repeat(' ', len(submatch(0))/2);g " Tab to 2 spaces %s/\t/ /g </code></pre></div>

#til #vim

Get the Previous Expression Value in IEx

September 9, 2019

When using Elixir, I’ve long missed the special <code>_</code> helper from <a href="https://en.wikipedia.org/wiki/Interactive_Ruby_Shell">irb</a> that returns the result of the previous expression. Sometimes I actually type it out of pure habit. Little did I know that Elixir has the same thing, except better. IEx.Helpers has a function <code>v(n \\ -1)</code> that returns the value of the nth expression in the session history. So <code>v</code> alone returns the previous expression and <code>v(-2)</code> returns the one before it. <div class="highlight"><pre class="highlight elixir"><code>iex(1)> "abc" iex(2)> "zyx" iex(3)> v "zyx" iex(4)> v(-3) "abc" </code></pre></div>

#elixir #til

Ruby Symbol and String Array Shorthand

August 27, 2019

Ruby has some handy Array shorthands, but I always forget which is which, so I thought I should write them down. <h3 id="symbol-array-shorthand">Symbol Array Shorthand:</h3> <div class="highlight"><pre class="highlight ruby"><code>%i{foo bar} # => [:foo, :bar] </code></pre></div> <h3 id="string-array-shorthand">String Array Shorthand:</h3> <div class="highlight"><pre class="highlight ruby"><code>%w{foo bar} # => ["foo", "bar"] </code></pre></div> Both also work with square brackets <code>%w[a b c]</code> or parenthesis <code>%i(a b c)</code>

#til #ruby

Running Elixir tests in VSCode

July 30, 2019

In Vim-land, I use the <a href="https://www.github.com/janko-m/vim-test">vim-test plugin</a> for quickly executing tests from a command line shortcut<a href="#fn1">1</a>. I wanted to reproduce this behavior in <a href="https://code.visualstudio.com">Visual Studio Code</a>, but I couldn’t find an extension that worked in multiple languages (namely, Ruby, Elixir, Javascript, and Elm). I’m mostly just using VSCode for Elixir, but I still liked the idea of finding a more general purpose solution. So instead I used VSCode’s support for <a href="https://code.visualstudio.com/docs/editor/tasks">Tasks</a> to build the functionality myself. So in my project’s <code>tasks.json</code> file, I have the following 3 tasks for running all tests, a single...

#vscode #elixir #testing

SSH Tunnels into Production Rails Database

July 25, 2019

Today I needed to access a production database for my Rails app directly using a GUI application on my mac, so I figured out that this can be done by creating an SSH tunnel like so: <div class="highlight"><pre class="highlight shell"><code>ssh -Ng -L <local-port>:<remote-host>:<remote-port> <user>@<remote-host> ssh -Ng -L 3307:100.64.26.11:3307 adam@100.64.26.11 </code></pre></div> And then, in your Rails app, update the database.yml as if you were connecting to a local database, but specify the proper database name. <div class="highlight"><pre class="highlight yaml"><code>development: adapter: mysql2 database: myapp_production host: 127.0.0.1 port: 3307 username: root password</code></pre></div>

#til #command-line #mysql #rails

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