cgrothaus

cgrothaus

3 different ways to build a list with conditional elements in Elixir (and what that has to do with application startup)

I wrote a blog post about 3 different ways to build a list with conditional elements in Elixir (and what that has to do with application startup).

Most Liked

Eiji

Eiji

There are other ways to achieve such results for example using recursive functions.

defmodule Example do
  def sample(list) do
    List.foldr(list, [], fn
      {false, _child_spec}, acc -> acc
      {true, child_spec}, acc -> [child_spec | acc]
      child_spec, acc -> [child_spec | acc]
    end)
  end

  def sample2([]), do: []
  def sample2([{false, _child_spec} | rest]), do: sample2(rest)
  def sample2([{true, child_spec} | rest]), do: sample2([child_spec | rest])
  def sample2([child_spec | rest]), do: [child_spec | sample2(rest)]
end

input = [:not_tuple, {false, :skip_me}, {true, :no_skip}]

Example.sample(input)
Example.sample2(input)

Helpful resources:

  1. List.foldr/3
  2. Patterns and Guards

Where Next?

Popular Backend topics Top

New
New
First poster: bot
Such inflammatory, much wow. Unfortunately, Haskell itself agrees. Some languages naturally lend themselves towards adoption. Some don’t...
New
First poster: bot
I wrote Python for the last 10 years, and I always tend to write code in a “functional” way - map, filter, lambda and so on, it makes me ...
New
axelson
I describe how we use Hot Reloading with Webpack to develop faster and show how to integrate Webpack 5, webpack-dev-server, and Phoenix f...
New
chikega
Mark Hoffman, the author of Programming WebAssembly in Rust, is a pretty hilarious lecturer if you like a dry sense of humor.
New
brainlid
In episode 78 of Thinking Elixir, we talk with Chase Granberry about Logflare. We learn why Chase started the company, what Logflare does...
New
Johannes-Werbrouck
In this blog post over on Fly.io I take a look at PHP 8.1’s new Enum class, and show you how it can be used to set up a level structure f...
New
brainlid
Jason Stiebs shows a couple ways for a LiveView to make it easy for users to click and copy an important value to their clipboard. He sho...
New
brainlid
In a 2 day spike, I created my own Elixir-based AI Personal Fitness Trainer! The surprising part for me was how useful and helpful I foun...
New

Other popular topics Top

New
PragmaticBookshelf
Learn from the award-winning programming series that inspired the Elixir language, and go on a step-by-step journey through the most impo...
New
PragmaticBookshelf
Write Elixir tests that you can be proud of. Dive into Elixir’s test philosophy and gain mastery over the terminology and concepts that u...
New
PragmaticBookshelf
Design and develop sophisticated 2D games that are as much fun to make as they are to play. From particle effects and pathfinding to soci...
New
PragmaticBookshelf
From finance to artificial intelligence, genetic algorithms are a powerful tool with a wide array of applications. But you don't need an ...
New
AstonJ
There’s a whole world of custom keycaps out there that I didn’t know existed! Check out all of our Keycaps threads here: https://forum....
New
AstonJ
I’ve been hearing quite a lot of comments relating to the sound of a keyboard, with one of the most desirable of these called ‘thock’, he...
New
AstonJ
I have seen the keycaps I want - they are due for a group-buy this week but won’t be delivered until October next year!!! :rofl: The Ser...
New
New
CommunityNews
A Brief Review of the Minisforum V3 AMD Tablet. Update: I have created an awesome-minisforum-v3 GitHub repository to list information fo...
New