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.

recode can correct and check the following things:

> mix recode.help

Design tasks:
TagFIXME          # Checker   - Checks if there are FIXME tags in the sources.
TagTODO           # Checker   - Checks if there are TODO tags in the sources.
Readability tasks:
AliasExpansion    # Corrector - Exapnds multi aliases to separate aliases.
AliasOrder        # Corrector - Checks if aliases are sorted alphabetically.
EnforceLineLength # Corrector - Forces expressions to one line.
Format            # Corrector - Does the same as `mix format`.
PipeFunOne        # Corrector - Add parentheses to one-arity functions.
SinglePipe        # Corrector - Pipes should only be used when piping data through multiple calls.
Specs             # Checker   - Checks for specs.
Refactor tasks:
FilterCount       # Corrector - Checks calls like Enum.filter(...) |> Enum.count().
Nesting           # Checker   - Checks code nesting depth in functions and macros.
Warning tasks:
Dbg               # Corrector - There should be no calls to dbg.
IOInspect         # Corrector - There should be no calls to IO.inspect.
TestFileExt       # Corrector - Checks the file extension of test files.
UnusedVariable    # Corrector - Checks if unused variables occur.

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, "~> 0.7", 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 recode a configuration file is needed.

mix recode.gen.config

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

[
  version: "0.7.0",
  # 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 overwritten by calling `mix recode "lib/**/*.ex"`.
  inputs: ["{mix,.formatter}.exs", "{apps,config,lib,test}/**/*.{ex,exs}"],
  formatters: [Recode.CLIFormatter],
  tasks: [
    # Tasks could be added by a tuple of the tasks module name and an options
    # keyword list. A task can be deactivated by `active: false`. The execution of
    # a deactivated task can be forced by calling `mix recode --task ModuleName`.
    {Recode.Task.AliasExpansion, []},
    {Recode.Task.AliasOrder, []},
    {Recode.Task.Dbg, [autocorrect: false]},
    {Recode.Task.EnforceLineLength, [active: true, exclude: "mix.exs"]},
    {Recode.Task.FilterCount, []},
    {Recode.Task.IOInspect, [autocorrect: false]},
    {Recode.Task.Nesting, []},
    {Recode.Task.PipeFunOne, []},
    {Recode.Task.SinglePipe, []},
    {Recode.Task.Specs, [exclude: "test/**/*.{ex,exs}", config: [only: :visible]]},
    {Recode.Task.TagFIXME, [exit_code: 2]},
    {Recode.Task.TagTODO, [exit_code: 4]},
    {Recode.Task.TestFileExt, []},
    {Recode.Task.UnusedVariable, [active: false]}
  ]
]

If a configuration file already exists, you can use the mix task

mix recode.update.config

to update the configuration file.

`mix recode`

This mix task runs the linter with autocorrection. The switch --dry (alias -d) prevents the update of the files and shows all changes in the console.

> cd examples/my_code
> mix recode --dry --no-color
Read 19 files in 0.05s
!.........!........!!...............................!................!...!......
.......................!...........................!..!!..........!.........!...
..............!.!......!......!.....!......!...............!..........!...!.....
...........!!..!.!!.!..
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/deep.ex
[Specs 2/3] Functions should have a @spec type specification.
[Nesting 6/11] The body is nested too deep (max depth: 2).

File: lib/my_code/empty.ex
Updates: 1
Changed by: Format

File: lib/my_code/multi.ex
Updates: 4
Changed by: SinglePipe, PipeFunOne, FilterCount, Format
 1  1   |defmodule MyCode.Multi do
 2    - |
 3  2   |  import MyCode.Fun
 4  3   |
     ...|
 6  5   |
 7  6   |  def pipe(x) do
 8    - |    x |> double |> double() |> dbg()
    7 + |    x |> double() |> double() |> dbg()
 9  8   |  end
10  9   |
11 10   |  def single(x) do
12    - |    x |> double()
   11 + |    double(x)
13 12   |  end
14 13   |
     ...|
19 18   |  def my_count(list) do
20 19   |    list
21    - |    |> Enum.filter(fn x -> rem(x, 2) == 0 end)
22    - |    |> Enum.count()
   20 + |    |> Enum.count(fn x -> rem(x, 2) == 0 end)
23 21   |    |> IO.inspect()
24 22   |  end
     ...|
[Specs 4/3] Functions should have a @spec type specification.
[Specs 6/3] Functions should have a @spec type specification.
[Dbg 7/34] There should be no calls to dbg.
[Specs 10/3] Functions should have a @spec type specification.
[Specs 14/3] Functions should have a @spec type specification.
[Specs 18/3] Functions should have a @spec type specification.
[IOInspect 21/8] There should be no calls to IO.inspect.

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/single_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: lib/my_code/tags.ex
[TagTODO 3/-] Found a tag: TODO: add docs
[TagFIXME 6/-] Found a tag: FIXME: add more functions
[Specs 7/3] Functions should have a @spec type specification.

File: lib/my_code/trailing_comma.ex
Updates: 2
Changed by: SinglePipe, Format
     ...|
 3  3   |
 4  4   |  def list do
 5    - |    [
    5 + |    Enum.reverse([
 6  6   |      100_000,
 7  7   |      200_000,
     ...|
14 14   |      900_000,
15 15   |      1_000_000,
16    - |      2_000_000,
17    - |    ] |> Enum.reverse()
   16 + |      2_000_000
   17 + |    ])
18 18   |  end
19 19   |end
     ...|

File: mix.exs
Updates: 1
Changed by: Format
     ...|
 9  9   |      start_permanent: Mix.env() == :prod,
10 10   |      deps: deps(),
11    - |      aliases: aliases(),
   11 + |      aliases: aliases()
12 12   |    ]
13 13   |  end
     ...|
16 16   |    [
17 17   |      extra_applications: [:logger],
18    - |      mod: {Recode.Application, []},
   18 + |      mod: {Recode.Application, []}
19 19   |    ]
20 20   |  end
     ...|
23 23   |    [
24 24   |      backup: ["cmd elixir ./scripts/backup.exs"],
25    - |      "backup.restore": ["cmd elixir ./scripts/backup.exs restore"],
   25 + |      "backup.restore": ["cmd elixir ./scripts/backup.exs restore"]
26 26   |    ]
27 27   |  end
     ...|
32 32   |      # dev/test
33 33   |      {:credo, "~> 1.6", only: [:dev, :test], runtime: false},
34    - |      {:freedom_formatter, "~> 2.1", only: :dev},
   34 + |      {:freedom_formatter, "~> 2.1", only: :dev}
35 35   |    ]
36 36   |  end
     ...|

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

Executed 244 tasks in 0.01s.
Files: 19 (.ex: 15, .exs: 4)
Moved 1 file
Updated 8 files
Found 15 issues
Finished in 0.06s.

The switch --no-autocorrect runs the linter without any file changes. In this mode, all correctors are working as checkers.

> 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.
[Dbg 9/32] There should be no calls to dbg.
[SinglePipe 13/7] Use a function call when a pipeline is only one function long.
[FilterCount 22/12] `Enum.count/2` is more efficient than `Enum.filter/2 |> Enum.count/1`
[IOInspect 24/8] There should be no calls to IO.inspect.

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

 File: lib/my_code/single_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.

Finished in 0.05 seconds.

With the switch --autocorrect (alias -a), correctors that are configured with autocorrect: false going into the corrections mode.

Use the switch --task (alias -t) to run a specific task. This switch can be used multiple times.

The last two switches are helpful for the task IOInspect and Dbg. Both of the tasks are correctors configured with autocorrect: false in the default configuration. The following example shows how to run these two tasks.

> cd examples/my_code
> mix recode -t IOInspect -t Dbg
Found 18 files, including 3 scripts.
....................................
 File: lib/my_code/multi.ex
[Dbg 9/32] There should be no calls to dbg.
[IOInspect 24/8] There should be no calls to IO.inspect.

Finished in 0.04 seconds.

To delete all occurrences of dbg and IO.inspect the following call can be used.

> cd examples/my_code
> mix recode -av -t IOInspect -t Dbg
Found 18 files, including 3 scripts.
....................................
 File: lib/my_code/multi.ex
Updates: 2
Changed by: Dbg, IOInspect
     ...|
 7  7   |
 8  8   |  def pipe(x) do
 9    - |    x |> double |> double() |> dbg()
    9 + |    x |> double |> double()
10 10   |  end
11 11   |
     ...|
22 22   |    |> Enum.filter(fn x -> rem(x, 2) == 0 end)
23 23   |    |> Enum.count()
24    - |    |> IO.inspect()
25 24   |  end
26 25   |end
     ...|

Finished in 0.04 seconds.

The -av stands for the switches --autocorrect and --verbose. The switch --verbose causes recode to display all changes as a diff on the console.

`mix format`

You can also run Recode together with mix format by adding Recode.FormatterPlugin to your .formatter.exs plugins:

[
  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"],
  plugins: [Recode.FormatterPlugin]
]

If you are using ElixirLS, you will need to enable recode for the test environment:

  def deps do
    [
      {:recode, "~> 0.7", only: [:dev, :test]}
    ]
  end

`mix recode.help`

The task recode.help prints all available recode-task with a short description.

The task prints the documentation for a given recode-task.

> mix recode.help Dbg
                                Recode.Task.Dbg

Calls to dbg/2 should only appear in debug sessions.

This task rewrites the code when mix recode runs with autocorrect: true.

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

hrzndhrn / recode