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
It’s not legacy code — it’s PHP. Vimeo has been using PHP in production for over 15 years. Find out how we keep a million lines of PHP i...
New
paulanthonywilson
I had a bit of a mini-adventure following Sobelow’s advice on adding a CSP to a Phoenix App. If you want to follow along, or want to add ...
New
paulanthonywilson
Post on using UDP multicasting with Elixir to broadcast presence, and listen for peers, on a local network. I have found this approach us...
New
First poster: Exadra37
Summary: I describe a simple interview problem (counting frequencies of unique words), solve it in various languages, and compare perform...
New
CommunityNews
Have you ever wanted to write a structurally typed function in Rust? Do you spend a lot of time and effort getting your Rust struct s jus...
New
brainlid
In episode 81 of Thinking Elixir, we talk with Digit and Quinn Wilton about the Burrito project. It wraps up Elixir to a single binary, e...
New
brainlid
In episode 83 of Thinking Elixir, We talk with Isaac Yonemoto about the Zig language and his Zigler Elixir library. We learn where Zig ca...
New
StuntProgrammer
In building lofi.limo, media storage and distribution naturally came up. I have songs, announcements, and background image loops which I ...
New

Other popular topics Top

PragmaticBookshelf
Stop developing web apps with yesterday’s tools. Today, developers are increasingly adopting Clojure as a web-development platform. See f...
New
siddhant3030
I’m thinking of buying a monitor that I can rotate to use as a vertical monitor? Also, I want to know if someone is using it for program...
New
AstonJ
Curious to know which languages and frameworks you’re all thinking about learning next :upside_down_face: Perhaps if there’s enough peop...
New
Exadra37
Oh just spent so much time on this to discover now that RancherOS is in end of life but Rancher is refusing to mark the Github repo as su...
New
DevotionGeo
The V Programming Language Simple language for building maintainable programs V is already mentioned couple of times in the forum, but I...
New
foxtrottwist
A few weeks ago I started using Warp a terminal written in rust. Though in it’s current state of development there are a few caveats (tab...
New
PragmaticBookshelf
Author Spotlight: VM Brasseur @vmbrasseur We have a treat for you today! We turn the spotlight onto Open Source as we sit down with V...
New
New
RobertRichards
Hair Salon Games for Girls Fun Girls Hair Saloon game is mainly developed for kids. This game allows users to select virtual avatars to ...
New
PragmaticBookshelf
Fight complexity and reclaim the original spirit of agility by learning to simplify how you develop software. The result: a more humane a...
New