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

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
Such inflammatory, much wow. Unfortunately, Haskell itself agrees. Some languages naturally lend themselves towards adoption. Some don’t...
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
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
This post explains why Scala projects are difficult to maintain. Scala is a powerful programming language that can make certain small te...
New
First poster: bot
Creation vs. Evolution Consider the history of Elixir: first you take Erlang, which was invented by Joe Armstrong and team to solve the ...
New
First poster: brennan
The perspective of an ignorant computer science undergrad It’s likely that you read the title of this post and thought “what is this guy ...
New
First poster: bot
This post is a spiritual successor to Loris Cro’s Go cross-compilation. The encounter During a recent stage 2 meeting Jakub Konka wanted...
New
chikega
Mark Hoffman, the author of Programming WebAssembly in Rust, is a pretty hilarious lecturer if you like a dry sense of humor.
New
mudasobwa
Peeper is the tiny library to preserve state across GenServer crashes/restarts. Works as an almost drop-in substitute for GenServer, sui...
New

Other popular topics Top

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
brentjanderson
Bought the Moonlander mechanical keyboard. Cherry Brown MX switches. Arms and wrists have been hurting enough that it’s time I did someth...
New
PragmaticBookshelf
Rust is an exciting new programming language combining the power of C with memory safety, fearless concurrency, and productivity boosters...
New
dimitarvp
Small essay with thoughts on macOS vs. Linux: I know @Exadra37 is just waiting around the corner to scream at me “I TOLD YOU SO!!!” but I...
New
Maartz
Hi folks, I don’t know if I saw this here but, here’s a new programming language, called Roc Reminds me a bit of Elm and thus Haskell. ...
New
DevotionGeo
I have always used antique keyboards like Cherry MX 1800 or Cherry MX 8100 and almost always have modified the switches in some way, like...
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
PragmaticBookshelf
Author Spotlight: Peter Ullrich @PJUllrich Data is at the core of every business, but it is useless if nobody can access and analyze ...
New
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