# `Bylaw.Credo.Check.Elixir.FilterRejectFirst`
[🔗](https://github.com/ryanzidago/bylaw/blob/v0.1.0-alpha.1/lib/bylaw/credo/check/elixir/filter_reject_first.ex#L1)

## Basics

> #### This check is disabled by default. {: .neutral}
>
> [Learn how to enable it](`e:credo:config_file.html#checks`) via `.credo.exs`.

This check has a base priority of `high` and works with any version of Elixir.

## Explanation

Use `Enum.find/2` when the code only needs the first item that matches a
predicate.

## Examples

Avoid:

      users
      |> Enum.filter(& &1.active?)
      |> List.first()

      List.first(Enum.reject(users, & &1.archived?))

Prefer:

      Enum.find(users, & &1.active?)
      Enum.find(users, &(not &1.archived?))

## Notes

`Enum.filter/2` and `Enum.reject/2` traverse the whole enumerable and
allocate an intermediate list before `List.first/1` discards everything
but the first item.

`Enum.find/2` stops as soon as it finds a matching item and states the
intent directly.

This check uses static AST analysis, so it favors clear source-level patterns over runtime behavior.

## Options

This check has no check-specific options. Configure it with an empty option list.

## Usage

Add this check to Credo's `checks:` list in `.credo.exs`:

```elixir
%{
  configs: [
    %{
      name: "default",
      checks: [
        {Bylaw.Credo.Check.Elixir.FilterRejectFirst, []}
      ]
    }
  ]
}
```

## Check-Specific Parameters

*There are no specific parameters for this check.*

## General Parameters

Like with all checks, [general params](`e:credo:check_params.html`) can be applied.

Parameters can be configured via the [`.credo.exs` config file](`e:credo:config_file.html`).

---

*Consult [api-reference.md](api-reference.md) for complete listing*