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

lpil
Shayne gave this excellent talk the other day on Gleam, so I thought I’d share it. From my point of view it was really interesting to se...
New
Scorpil
I dabbled in Phoenix for a while now, but never really got my hands dirty with it right up until now. Apart from the whole framework bein...
New
First poster: bot
In a previous post we talked about implementing a simple video chat with WebRTC and Elixir. This update will touch on some of the API cha...
New
First poster: bot
It’s easy to view yourself as “not a real programmer.” There are programs out there that everyone uses, and it’s easy to put their develo...
/c
New
CommunityNews
This thread was posted by one of our members via one of our news source trackers.
New
First poster: bot
PHP 8.1 is already taking shape quite well, yet there’s one feature I’d love to see added, that’s still being discussed: multi-line short...
New
ragamuf
Does the world need another How to create a blog article? Maybe not. But then again, creating something out of nothing is what we love....
New
MarcinKasprowicz
Elixir language viewed from the perspective of a JavaScript developer. I compared selected aspects of the two languages and touched on to...
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
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

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
PragmaticBookshelf
Rust is an exciting new programming language combining the power of C with memory safety, fearless concurrency, and productivity boosters...
New
AstonJ
This looks like a stunning keycap set :orange_heart: A LEGENDARY KEYBOARD LIVES ON When you bought an Apple Macintosh computer in the e...
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
Margaret
Hello everyone! This thread is to tell you about what authors from The Pragmatic Bookshelf are writing on Medium.
1147 29994 760
New
AstonJ
We’ve talked about his book briefly here but it is quickly becoming obsolete - so he’s decided to create a series of 7 podcasts, the firs...
New
PragmaticBookshelf
Rails 7 completely redefines what it means to produce fantastic user experiences and provides a way to achieve all the benefits of single...
New
PragmaticBookshelf
Build efficient applications that exploit the unique benefits of a pure functional language, learning from an engineer who uses Haskell t...
New
New
PragmaticBookshelf
Develop, deploy, and debug BEAM applications using BEAMOps: a new paradigm that focuses on scalability, fault tolerance, and owning each ...
New