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
Rust vs Go — Bitfield Consulting. Which is better, Rust or Go? Which language should you choose for your next project, and why? How do t...
New
First poster: bot
We all know how to teach recursion. We’ve done it for decades. We pick some honored, time-tested examples—Fibonacci numbers and factorial...
New
First poster: AstonJ
Ten years without Elixir. I never got into Elixir, largely because it looked like Ruby. I was a Rubyist for a good while, spent time and...
New
AstonJ
Just finished doing a clean install of macOS (which I highly recommend btw!) and have updated my macOS Ruby & Elixir/Erlang dev env s...
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
CommunityNews
Functional programming is an increasing popular programming paradigm with many languages building or already supporting it. Go already su...
New
New
tonyxrandall
As DoorDash transitioned from Python monolith to Kotlin microservices, our engineering team was presented with a lot of opportunities to ...
New
StuntProgrammer
In building lofi.limo, media storage and distribution naturally came up. I have songs, announcements, and background image loops which I ...
New
brainlid
Episode 244 of Thinking Elixir. News includes the release of Elixir 1.18.2 with various enhancements and bug fixes, a new experimental SQ...
New

Other popular topics Top

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
New
New
PragmaticBookshelf
Author Spotlight Mike Riley @mriley This month, we turn the spotlight on Mike Riley, author of Portable Python Projects. Mike’s book ...
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
hilfordjames
There appears to have been an update that has changed the terminology for what has previously been known as the Taskbar Overflow - this h...
New
First poster: bot
zig/http.zig at 7cf2cbb33ef34c1d211135f56d30fe23b6cacd42 · ziglang/zig. General-purpose programming language and toolchain for maintaini...
New
New
PragmaticBookshelf
Explore the power of Ash Framework by modeling and building the domain for a real-world web application. Rebecca Le @sevenseacat and ...
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