over enumerables according to the Enumerable protocol. iex> Enum.map([1, 2, 3], fn(x) -> x * 2 end) [2, 4, 6] Some particular types, like maps, yield a specific format on enumeration. For example, the argument is always a {key, value} tuple for maps: iex> map = %{a: 1, b: 2} iex> Enum.map(map, fn {k, v} -> {k, v * 2} end) [a: 2, b: 4] Note that the functions in the Enum module are eager: they always start the enumeration of the given enumerable. The Stream module allows lazy enumeration of enumerables and provides infinite streams. Since the majority of the functions in Enum enumerate the whole enumerable and return a list as result, infinite streams need to be carefully used with such functions, as they can potentially run forever. For example: Enum.each Stream.cycle([1, 2, 3]), &IO.puts(&1)
end) @spec min_max(t(), (() -> empty_result)) :: {element(), element()} | empty_result | no_return() when empty_result: any() Returns a tuple with the minimal and the maximal elements in the enumerable according to Erlang's term ordering. If multiple elements are considered maximal or minimal, the first one that was found is returned. Calls the provided empty_fallback function and returns its value if enumerable is empty. The default empty_fallback raises Enum.EmptyError. ## Examples iex> Enum.min_max([2, 3, 1]) {1, 3} iex> Enum.min_max([], fn -> {nil, nil} end) {nil, nil}
case get_in(item,[:secret, :details, :id]) do nil -> :error identifier -> identifier end Find identifier: %{secret: %{details: %{id: identifier}}} You can fetch structure: item = MyRepo.Items.find_by_resource("book") case item.secret do nil -> :error secret -> case secret.details do nil -> :error details -> case details.id do nil -> :error identifier -> identifier end end end
:test], runtime: false} Prepare new alias to enable strict mode check defp aliases do [ "credo": ["credo —strict"] ] end mix deps.get Update mix.lock file - download package and append to project * You can adjust settings to your preferences - configure .credo file
ensure a consistent coding style. Using tabs or spaces? Both is fine, just don't mix them or Credo will tell you. Readability Readability checks do not concern themselves with the technical correctness of your code, but how easy it is to digest. Refactoring Opportunities The Refactor checks show you opportunities to avoid future problems and technical debt. Software Design While refactor checks show you possible problems, these checks try to highlight possibilities, like - potentially intended - duplicated code or TODO: and FIXME annotations. Warnings These checks warn you about things that are potentially dangerous, like a missed call to IEx.pry or a call to String.downcase without saving the result.
Code Readability ┃ ┃ [R] → Modules should have a @moduledoc tag. ┃ apps/plant_monitor/lib/plant_monitor/oauth/permissions_service.ex:1:11 #(PlantMonitor.OAuth.PermissionService Consistency ┃ ┃ [C] ↗ There is no whitespace around parentheses/brackets most of the time, but ┃ here there is. ┃ apps/plant_monitor_web/lib/plant_monitor_web/controllers/api/authorized_user_controller.ex:21 #(PlantMonitorWeb.API.AuthorizedUserController.index) Please report incorrect results: https://github.com/rrrene/credo/issues Analysis took 3.5 seconds (1.5s to load, 2.0s running checks) 276 mods/funs, found 1 consistency issue, 1 code readability issue.
String.t() ## Returns PlantMonitor.User -> user found nil -> no user found """ @type fetch_response :: %PlantMonitor.User{} | nil @spec fetch_user_by_email(email :: String.t()) :: fetch_response def fetch_user_by_email(email) do User |> where([u], u.email == ^email) |> Repo.one() end
String.t() ## Returns PlantMonitor.User -> user found nil -> no user found """ @type fetch_response :: %PlantMonitor.Data{} | nil @spec fetch_user_by_email(email :: String.t()) :: fetch_response def fetch_user_by_email(email) do User |> where([u], u.email == ^email) |> Repo.one() end
String.t() ## Returns PlantMonitor.User -> user found nil -> no user found """ @type fetch_response :: %PlantMonitor.Data{} | nil @spec fetch_user_by_email(email :: String.t()) :: fetch_response def fetch_user_by_email(email) do User |> where([u], u.email == ^email) |> Repo.one() end apps/plant_monitor/lib/plant_monitor/user/service.ex:84: The pattern Vuser@1 = #{'id':=Vuser_id@1, 'permissions':=Vpermissions@1, '__struct__':='Elixir.PlantMonitor.User'} can never match the type 'nil' | #{'__meta__':=_, '__struct__':='Elixir.PlantMonitor.Data', 'air_humidity':=_, 'air_temperature':=_, 'device_id':=_, 'id':=_, 'inserted_at':=_, 'liquid_level_millimeters':=_, 'soil_humidity':=_, 'updated_at':=_} apps/plant_monitor/lib/plant_monitor/user/service.ex:94: Function validate_password/2 will never be called apps/plant_monitor_web/lib/plant_monitor_web/controllers/api/session_controller.ex:26: The pattern {'ok', Vtoken_details@1} can never match the type {'error','invalid_credentials'} done (warnings were emitted)
a string. """ @type number_with_remark :: {number, String.t()} @spec add(number, number) :: number_with_remark def add(x, y), do: {x + y, "You need a calculator to do that?"} @spec multiply(number, number) :: number_with_remark def multiply(x, y), do: {x * y, "It is like addition on steroids."} end Typespecs and behaviours
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![iex(1)> new_subscribers = Enum.reject(state.subscribers, &(&1 == pid)) [] iex(2)> Enum.reduce([1,2,3],](https://files.speakerdeck.com/presentations/2900d3cd7214471097ba604f0fbc7325/slide_15.jpg){kind=link}
![case item[:secret][:details][:id] do nil -> :error identifier -> identifier end](https://files.speakerdeck.com/presentations/2900d3cd7214471097ba604f0fbc7325/slide_27.jpg){kind=link}
