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

First poster: bot
One of my favourite programming languages in the last few years has been Crystal. While the language has not yet reached its 1.0 version,...
New
First poster: bot
In this post we’re going to be looking at a more advanced use of Gleam’s type system, known as phantom types. Hopefully by the end of thi...
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: bot
Just a small test with lists in cython. Considering echosystem, multithreading and ease of use, Julia is a clear winner here.
New
First poster: bot
I’ve been more serious about learning Rust recently, after dragging on with passive learning for a while. My first real programming langu...
New
First poster: bot
Too long have we hustled to deploy Clojure websites. Too long have we spun up one server instance per site. Too long have reminisced abou...
New
pablocostass
Todos coñecemos os focos de Erlang/Elixir máis renomeados do mundo, como a Suecia, o Brasil, a California ou Londres. Mais a comunidade, ...
New
wolf4earth
Louis Pilfold is the creator of the Gleam programming language. He explains what Gleam is and tells us where it came from. He then dives...
New
brainlid
There is a new community resource available on writing “Safe Ecto Migrations”. When we get a migration wrong, it can lock up your product...
New
mtmattei
For the past few years, Safari has been putting in a lot of effort to enhance its WebAssembly support and 2024 was no exception… I believ...
New

Other popular topics Top

ohm
Which, if any, games do you play? On what platform? I just bought (and completed) Minecraft Dungeons for my Nintendo Switch. Other than ...
New
wolf4earth
@AstonJ prompted me to open this topic after I mentioned in the lockdown thread how I started to do a lot more for my fitness. https://f...
New
Exadra37
I am thinking in building or buy a desktop computer for programing, both professionally and on my free time, and my choice of OS is Linux...
New
Exadra37
Please tell us what is your preferred monitor setup for programming(not gaming) and why you have chosen it. Does your monitor have eye p...
New
Rainer
My first contact with Erlang was about 2 years ago when I used RabbitMQ, which is written in Erlang, for my job. This made me curious and...
New
AstonJ
If you are experiencing Rails console using 100% CPU on your dev machine, then updating your development and test gems might fix the issu...
New
PragmaticBookshelf
Create efficient, elegant software tests in pytest, Python's most powerful testing framework. Brian Okken @brianokken Edited by Kat...
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 Jamis Buck @jamis This month, we have the pleasure of spotlighting author Jamis Buck, who has written Mazes for Prog...
New
AstonJ
Curious what kind of results others are getting, I think actually prefer the 7B model to the 32B model, not only is it faster but the qua...
New