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.