Recode

A linter with autocorrection.

recode is an experimental project to play around with the great sourceror package by @doorgan.

This library is still under development, breaking changes are expected. The same is true for sourceror and most of recode's functionality is based on sourceror.

For now, recode corrects only a few things:

• AliasExpansion expands multi aliases
• AliasOrder orders aliases alphabetically
• Format runs the Elixir formatter
• PipeFunOne adds () to one arity functions in pipes
• SinglePipe corrects single pipes
• TestFileExt renames test file extensions to *.exs

It is also possible to run recode in a none-autocorrect mode to just lint your code.

Installation

The package can be installed by adding recode to your list of dependencies in mix.exs:

  def deps do
    [
      {:recode, "~> 0.4", only: :dev}
    ]
  end

Recode requires Elixir 1.13.0 or higher. If you add recode to a project that supports lower Elixir versions you could add recode as following:

  def deps do
    [
      # your deps
    ] ++ recode()
  end

  defp recode() do
    case Version.match?(System.version(), "~> 1.13") do
      true -> [{:recode, "~> 0.4", only: :dev}]
      false -> []
    end
  end

Documentation can be found at https://hexdocs.pm/recode.

Usage

To start with Foo a configuration file is needed.

mix recode.gen.config

This mix task generates the config file .recode.exs.

alias Recode.Task

[
  version: "0.4.0",
  # Can also be set/reset with "--autocorrect"/"--no-autocorrect".
  autocorrect: true,
  # With "--dry" no changes will be written to the files.
  # Can also be set/reset with "--dry"/"--no-dry".
  # If dry is true then verbose is also active.
  dry: false,
  # Can also be set/reset with "--verbose"/"--no-verbose".
  verbose: false,
  # Can be overwriten by calling `mix recode "lib/**/*.ex"`.
  inputs: ["{config,lib,test}/**/*.{ex,exs}"],
  formatter: {Recode.Formatter, []},
  tasks: [
    # Tasks could be added by a tuple of the tasks module name and an options
    # keyword list. A task can be deactived by `active: false`. The execution of
    # a deactivated task can be forced by calling `mix recode --task ModuleName`.
    {Task.AliasExpansion, []},
    {Task.AliasOrder, []},
    {Task.EnforceLineLength, active: false},
    {Task.PipeFunOne, []},
    {Task.SinglePipe, []},
    {Task.Specs, exclude: "test/**/*.{ex,exs}", config: [only: :visible]},
    {Task.TestFileExt, []},
    {Task.UnusedVariable, active: false}
  ]
]

mix recode

This mix tasks runs the linter with autocorrection. The switch --dry prevents the update of the files and shows all changes in the console.

> cd examples/my_code
> mix recode --dry
Found 13 files, including 2 scripts.
...........................................................................................
 File: lib/my_code.ex
[Specs 15/3] Functions should have a @spec type specification.

 File: lib/my_code/alias_expansion.ex
Updates: 1
Changed by: AliasExpansion
1 1   |defmodule MyCode.AliasExpansion do
2   - |  alias MyCode.{PipeFunOne, SinglePipe}
  2 + |  alias MyCode.PipeFunOne
  3 + |  alias MyCode.SinglePipe
3 4   |
4 5   |  def foo(x) do
   ...|
[Specs 5/3] Functions should have a @spec type specification.

 File: lib/my_code/alias_order.ex
Updates: 2
Changed by: AliasOrder, AliasExpansion
     ...|
12 12   |
13 13   |defmodule Mycode.AliasOrder do
14    - |  alias MyCode.SinglePipe
   14 + |  alias MyCode.Echo
   15 + |  alias MyCode.Foxtrot
15 16   |  alias MyCode.PipeFunOne
16    - |  alias MyCode.{Foxtrot, Echo}
   17 + |  alias MyCode.SinglePipe
17 18   |
18 19   |  @doc false
     ...|

 File: lib/my_code/fun.ex
Updates: 1
Changed by: Format
     ...|
 2  2   |  @moduledoc false
 3  3   |
 4    - |
 5    - |
 6    - |
 7    - |
 8    - |
 9  4   |  def noop(x), do: x
10  5   |end
     ...|

 File: lib/my_code/multi.ex
Updates: 2
Changed by: SinglePipe, PipeFunOne
     ...|
 7  7   |
 8  8   |  def pipe(x) do
 9    - |    x |> double |> double()
    9 + |    x |> double() |> double()
10 10   |  end
11 11   |
12 12   |  def single(x) do
13    - |    x |> double()
   13 + |    double(x)
14 14   |  end
15 15   |
     ...|

 File: lib/my_code/pipe_fun_one.ex
Updates: 1
Changed by: PipeFunOne
     ...|
 5  5   |
 6  6   |  def pipe(x) do
 7    - |    x |> double |> double()
    7 + |    x |> double() |> double()
 8  8   |  end
 9  9   |end
     ...|

 File: lib/my_code/same_line.ex
[Specs 2/3] Functions should have a @spec type specification.

 File: lib/my_code/singel_pipe.ex
Updates: 1
Changed by: SinglePipe
     ...|
 5  5   |
 6  6   |  def single_pipe(x) do
 7    - |    x |> double()
    7 + |    double(x)
 8  8   |  end
 9  9   |
10    - |  def reverse(a), do: a |> Enum.reverse()
   10 + |  def reverse(a), do: Enum.reverse(a)
11 11   |end
12 12   |

 File: test/my_code_test.exs
Updates: 1
Changed by: TestFileExt
Moved from: test/my_code_test.ex

The switch --no-autocorrect runs the linter without any file changes.

> cd examples/my_code
> mix recode --no-autocorrect
Found 11 files, including 2 scripts.
.............................................................................
 File: lib/my_code.ex
[Specs 15/3] Functions should have a @spec type specification.

 File: lib/my_code/alias_expansion.ex
[AliasExpansion 2/3] Avoid multi aliases.
[Specs 4/3] Functions should have a @spec type specification.

 File: lib/my_code/alias_order.ex
[AliasOrder 15/3] The alias `MyCode.PipeFunOne` is not alphabetically ordered among its group
[AliasOrder 16/3] The alias `MyCode` is not alphabetically ordered among its group
[AliasOrder 16/26] The alias `Echo` is not alphabetically ordered among its multi group
[AliasExpansion 16/3] Avoid multi aliases.

 File: lib/my_code/fun.ex
[Format -/-] The file is not formatted.

 File: lib/my_code/multi.ex
[PipeFunOne 9/7] Use parentheses for one-arity functions in pipes.
[SinglePipe 13/7] Use a function call when a pipeline is only one function long.

 File: lib/my_code/pipe_fun_one.ex
[PipeFunOne 7/7] Use parentheses for one-arity functions in pipes.

 File: lib/my_code/singel_pipe.ex
[SinglePipe 7/7] Use a function call when a pipeline is only one function long.
[SinglePipe 10/25] Use a function call when a pipeline is only one function long.

 File: test/my_code_test.ex
[TestFileExt -/-] The file must be renamed to test/my_code_test.exs so that ExUnit can find it.

Differences to Credo

recode was started as a plugin for credo. Unfortunately it was not possible to implement autocorrection as a plugin because Credo's traversal of the code does not support changing the code.

Maybe some code lines from recode could be used as inspiration for credo to bring the autocorrect feature to credo.

Other differences:

• recode requires Elixir 1.13, credo requires Elixir 1.7
• recode has autocorrection
• credo has much more checkers
• credo is faster
• credo has more features