Capturing individual measurements from your projects isn’t enough. For measurements to be valuable, they must be collated into metrics. Elixir’s Telemetry.Metrics library enables us to aggregate measurements from functions and processes into valuable metrics to aid us in making decisions about our projects.

Elixir Telemetry: Metrics and Reporters

Solution is a library to help you with working with ok/error-tuples in case and with-expressions by exposing special matching macros, as well as some extra helper functions to work with them in collections.

An example:

 x = {:ok, 10}
 y = {:ok, 42, "Oh, here's another argument!"}
 z = {:ok, "something we do not care about"}
 swith ok(res) <- x,
       ok(res2) <- y,
       ok() <- z do
      "We have: \#{res} \#{res2}"
    else
      other -> "Failure at #{inspect(other)}"
  end
# => "We have: 10 33"

Note how it did not matter that y contains more than one value in the tuple, or that z does not return a plain :ok. But if they would have, the outcome of the code would have been exactly the same.

Solution handles these cases for you exactly to allow you to have less of a tight coupling between the places where an ok/error tuple is returned and where it is used:

• If at some point a caller decides to change from :ok to {:ok, some_value}, then that will not break your code.
• If at some point a caller decides to change from {:ok, some_value} to {:ok, some_value, some_metadata}, then that will not break your code.

Besides allowing tricks like above, Solution also contains a small module containing some helper functions to combine collections of ok/error tuples in common ways.

Find it at: HexPM, GitHub, ElixirForum.

Ever stumped trying to get output from a port?

Rambo has one mission. Start your program, pipe standard input, send EOF and return with output.

Rambo.run("ls") |> Rambo.run("sort") |> Rambo.run("head")

https://github.com/jayjun/rambo

Pachyderm is built to allow developers to work with “effectively” unique processes

https://github.com/CrowdHailer/pachyderm

GitHub recently released their own CI. solution recently. Its documentation is kind of overwhelming, so I wrote a step-by-step guide for testing a phoenix + postgres app in GitHub CI.

https://nickvernij.nl/blog/github-ci-elixir.html

I created a simple tool using Elixir, React and Redux which shows the returns of a financial portfolio over time. It enables users to change a set of parameters (e.g. region, monthly deposits, rebalancing strategy), and compare the results.

https://elviovicosa.com/permanent-portfolio/

Grapevine is a community site for text based games (MUDs). It’s an open source application so you can see how it all works! The latest updates are better stats and a web chat that was rebuilt with React.

https://blog.oestrich.org/2019/08/grapevine-updates

Extremely biased and exaggerated writing on why I personally think the tests are overrated and in some cases bring more harm than profit.

http://rocket-science.ru/hacking/2019/08/28/beware-of-tests-et-fiducia-ferentes

In this episode of ElixirMix, we talk with John Mertens about how Change.org Elixir to deliver huge numbers of messages. We discuss Flow vs Broadway, how Plataformatec was involved, the importance of observability, and much more!

Podcast Episode

Use Elixir and Phoenix to host the landing pages for all of your pending projects!

https://nerves.build/posts/DomainHolding

This release brings the support of windows, the new version 6.2.2 of rocksdb and some other fixes.

Mor info about the release on Gitlab: https://gitlab.com/barrel-db/erlang-rocksdb

To get started: https://gitlab.com/barrel-db/erlang-rocksdb

Enjoy!

Benoît

In this post I cover about the “Permanent Portfolio”, and how to use Elixir and real-time pricing information to rebalance the portfolio and profit from that.

https://elviovicosa.com/2019/08/25/financial-portfolio-rebalancing-with-elixir/

https://phxroad.com/guides/add-authentication-to-phoenix-with-pow/

How to learn from Broadway architecture to build internal packages simplifying business logic encapsulation.

http://rocket-science.ru/hacking/2019/08/26/behaviour-backed-scaffolds

How to create embedded schemas in Ecto to save a JSON data structure on your database + how to implement a direct database search on this same field.

Read more on Coletiv Blog

Learn how to analyze and validate Elixir code by taking a mind-blowing journey through string scanning, AST traversal and code compilation.

Read more on Cloudless Studio blog.

I would like to present a new library for convenient work with Avro serialization – Avrora.

It supports encoding/decoding:

1. Avro Object Container Files format
2. Confluent Schema Registry format
3. Plain messages format (when you just want a message body)

In the case of the schema registry, it will also a register new schema. Here is an example with Object Container Files.

Let’s say you have this Payment schema stored in a file priv/schemas/io/confluent/Payment.avsc

{
  "type": "record",
  "name": "Payment",
  "namespace": "io.confluent",
  "fields": [
    {
      "name": "id",
      "type": "string"
    },
    {
      "name": "amount",
      "type": "double"
    }
  ]
}

To encode payment message with Payment.avsc schema

iex> {:ok, pid} = Avrora.start_link()
iex> message = %{"id" => "tx-1", "amount" => 15.99}
iex> {:ok, encoded} = Avrora.encode(message, schema_name: "io.confluent.Payment")

<<79, 98, 106, 1, 3, 204, 2, 20, 97, 118, 114, 111, 46, 99, 111,
  100, 101, 99, 8, 110, 117, 108, 108, 22, 97, 118, 114, 111, 46,
  115, 99, 104, 101, 109, 97, 144, 2, 123, 34, 110, 97, 109, 101,
  115, 112, 97, 99, 101, 34, 58, 34, 105, 111, 46, 99, 111, 110,
  102, 108, 117, 101, 110, 116, 34, 44, 34, 110, 97, 109, 101, 34,
  58, 34, 80, 97, 121, 109, 101, 110, 116, 34, 44, 34, 116, 121,
  112, 101, 34, 58, 34, 114, 101, 99, 111, 114, 100, 34, 44, 34,
  102, 105, 101, 108, 100, 115, 34, 58, 91, 123, 34, 110, 97, 109,
  101, 34, 58, 34, 105, 100, 34, 44, 34, 116, 121, 112, 101, 34, 58,
  34, 115, 116, 114, 105, 110, 103, 34, 125, 44, 123, 34, 110, 97,
  109, 101, 34, 58, 34, 97, 109, 111, 117, 110, 116, 34, 44, 34,
  116, 121, 112, 101, 34, 58, 34, 100, 111, 117, 98, 108, 101, 34,
  125, 93, 125, 0, 138, 124, 66, 49, 157, 51, 242, 3, 33, 52, 161,
  147, 221, 174, 114, 48, 2, 26, 8, 116, 120, 45, 49, 123, 20, 174,
  71, 225, 250, 47, 64, 138, 124, 66, 49, 157, 51, 242, 3, 33, 52,
  161, 147, 221, 174, 114, 48>>

iex> {:ok, decoded} = Avrora.decode(message, schema_name: "io.confluent.Payment")

%{"id" => "tx-1", "amount" => 15.99}

Easy as it should be! Yaw ❤️

In this post, you’ll learn why and when you might want to use Ecto.Query#select_merge/3 when querying data from unassociated tables: https://medium.com/flatiron-labs/til-how-to-select-merge-with-ecto-query-679d03204b9d

https://medium.com/blackode/elixir-code-refactoring-techniques-33589ac56231

This article comprises of common Elixir coding techniques that you may or may not know.

A Jist of the Article

We usually encounter a situation like we expect a map has certain key and if not we need to send some default value.

Immediately, we will end up using Map.has_key? like in the following way

currency = 
  if(Map.has_key? price, "currency") do
    price["currency"]
  else
    "USD"

If you see any such lines in your code then it is time to refactor them as

currency = Map.get(price, "currency", "USD")

However, you can also take this to the next level like

currency = price["currency"] || "USD"

In this article, I want to describe how you can use elixir metaprogramming to avoid some runtime errors caused by typos. If you’re passing around some handcrafted messages ex. %{name: “app_one_hello”, payload: “payload”} you can easily introduce errors. Sending app_one_hello and listening for app_ane_hello will not make your system works correctly. Imagine you have thousands of messages. It’s really hard to manage them like that. To make things better, you can create a list of all messages and generate functions to send and receive them. Now when you will create a typo, elixir’s compiler will tell you!

Full article here: https://puddleofcode.com/story/how-to-use-elixir-s-compiler-to-avoid-typos