Today I Learned

A Hashrocket project

Using When Clauses In A With Construct In Elixir

Because Elixir’s with construct supports the full power of the language’s pattern matching, we can use when clauses to further narrow down our matches.

For instance, if we want to match against the response to an API request, but only for response status codes in the 2xx range, we can do something like the following:

with %{status_code: code, body: body}
       when code >= 200 && code < 300 <- HTTPoison.get!(url),
     {:ok, decoded_body} <- Poison.decode(body) do
  {:ok, decoded_body}

See the docs for with for more details.

Looking for help? Elixir is quickly gaining momentum for web applications that need concurrency, performance, and the ability to connect to many different clients. The developers at Hashrocket are learning along with the rest of the development community that Elixir and Phoenix are viable Rails alternatives for the right application. Check out the source code for Today I Learned, written in Elixir, and contact us if you need help with your Elixir project.