Bylaw.Credo.Check.Elixir.NoCatchAllInWithElse (bylaw_credo v0.4.0)

Basics

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

Explanation

Prefer explicit pattern matches in with else clauses over catch-all variables.

A catch-all branch can silently accept an unexpected result shape and blur which failures the caller intentionally handles. Explicit patterns document the error contract and leave unrecognized failures visible for deliberate handling.

Examples

Each else branch should match a specific pattern so that success and failure paths are clearly separated. Avoid:

  with {:ok, user} <- fetch_user(id) do
    {:ok, user}
  else
    error -> error
  end

Prefer:

  with {:ok, user} <- fetch_user(id) do
    {:ok, user}
  else
    {:error, error} -> {:error, error}
  end

Notes

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:

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

Check-Specific Parameters

There are no specific parameters for this check.

General Parameters

Like with all checks, general params can be applied.

Parameters can be configured via the .credo.exs config file.