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
First poster: bot
Why Zig When There is Already C++, D, and Rust? No hidden control flow No hidden allocations First-class support for no standard library...
New
AstonJ
Not had time to read it yet but this looks like a good interview… Our friend Yukihiro Matsumoto, creator of the Ruby programming langua...
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
Functional programming is an increasing popular programming paradigm with many languages building or already supporting it. Go already su...
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
We take a deeper dive with Nathan Long into IOLists in Elixir. We cover what they are, how they work, the power they have when concatenat...
New
wolf4earth
Charles Max Wood takes the lead this week. He and Adi Iyengar discuss what Top End Devs are and what people should be doing to become Top...
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
First poster: AstonJ
Ruby’s Struct is one of several powerful core classes which is often overlooked and under utilized compared to the more popular Hash clas...
New

Other popular topics Top

Devtalk
Hello Devtalk World! Please let us know a little about who you are and where you’re from :nerd_face:
New
Exadra37
I am asking for any distro that only has the bare-bones to be able to get a shell in the server and then just install the packages as we ...
New
PragmaticBookshelf
Build highly interactive applications without ever leaving Elixir, the way the experts do. Let LiveView take care of performance, scalabi...
New
PragmaticBookshelf
Use WebRTC to build web applications that stream media and data in real time directly from one user to another, all in the browser. ...
New
PragmaticBookshelf
Build efficient applications that exploit the unique benefits of a pure functional language, learning from an engineer who uses Haskell t...
New
PragmaticBookshelf
Author Spotlight Rebecca Skinner @RebeccaSkinner Welcome to our latest author spotlight, where we sit down with Rebecca Skinner, auth...
New
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
Margaret
Ask Me Anything with Mark Volkmann @mvolkmann On February 24 and 25, we are giving you a chance to ask questions of PragProg author M...
New
Fl4m3Ph03n1x
Background Lately I am in a quest to find a good quality TTS ai generation tool to run locally in order to create audio for some videos I...
New