Elixir v1.13.0-rc.0 released

Release: Release v1.13.0-rc.0 · elixir-lang/elixir · GitHub

The focus behind Elixir v1.13 has been on tooling, mainly tooling related to code formatting, code fragments, code reflection, and code recompilation. A lot of this functionality will directly impact developers working on large codebases and provide meaningful quality of life improvements for those working on Elixir tooling and environments, such as IDEs, notebooks, etc.

Semantic recompilation

Elixir v1.13 comes with many improvements to the compiler, so it recompiles your files less frequently. In particular:

  • The digest of the files are considered in addition to their size. This avoids recompiling many files when switching or rebasing branches.

  • Changing your mix.exs will no longer trigger a full recompilation, unless you specifically change the configurations used by the Elixir compiler (:elixirc_paths and :elixirc_options).

  • Changing compile-time configuration files (config/config.exs and any other file imported from it) now only recompiles the project files that depend on the reconfigured applications, instead of a full recompilation. However, if you change the configuration of your application itself, the whole project is still recompiled.

  • Adding, updating or removing a dependency now only recompiles the project files that depend on the modified a dependency.

  • If your project has both Erlang and Elixir files, changing an Erlang file will now recompile only the Elixir files that depend on it.

In a nutshell, Elixir went from triggering full recompilations whenever any of mix.exs, config/config.exs, src/*, and mix.lock changed on disk to semantic recompilations. Now it only fully recompiles when:

  • you change the compilation options in mix.exs
  • you change the configuration for the current project in config/config.exs

mix xref

mix xref is a tool that analyzes relationships between files. By analyzing the compile-time and runtime dependencies between files, it allows developers to understand what files have to be recompiled whenever a file changes.

Elixir v1.13 comes with many improvements to mix xref, such as:

  • mix xref graph now supports --label to be set to “compile-connected”, which returns all compile-time dependencies that lead to additional transitive dependencies.

  • A new mix xref trace FILE subcommand receives a file and returns all dependencies in said file, including the line and what caused said dependency (a function/macro call, an alias, a struct, etc).

  • All mix xref subcommands support the --fail-above flag, which allows you to enforce your project has at most a certain number of compile-time cycles, transitive compile-time dependencies, etc.

  • mix xref graph now supports multiple --sink and --source to be given.

With these improvements, it has become simpler to understand the impact code recompilation has in our codebases and how to limit it.

Code fragments

The Code module got a companion module called Code.Fragment, which hosts functions that work on incomplete code, as is often the scenario in editors, interactive shells, etc. The module contains different heuristics to analyze the source code and return context informational.

Thanks to these improvements, IEx’ autocomplete got several quality of life improvements, such as the autocompletion of sigils, structs, and paths. For example, typing ~<TAB> now shows:

iex(1)> ~
~C (sigil_C)    ~D (sigil_D)    ~N (sigil_N)    ~R (sigil_R)
~S (sigil_S)    ~T (sigil_T)    ~U (sigil_U)    ~W (sigil_W)
~c (sigil_c)    ~r (sigil_r)    ~s (sigil_s)    ~w (sigil_w)

Adding the sigil letter and pressing tab then shows the available delimiters:

iex(1)> ~r
"      """    '      '''    (      /      <      [      {      |

Similarly, %<TAB> now shows only the available structs (exceptions excluded), instead of all modules:

iex(1)> %File.St
File.Stat      File.Stream

Once you define the struct, you can hit tab to show all struct fields available:

iex(1)> %URI{
authority:    fragment:     host:         path:         port:
query:        scheme:       userinfo:

As you fill a field in, the already filled fields no longer show up:

iex(1)> %URI{path: "/example",
authority:    fragment:     host:         port:         query:
scheme:       userinfo:

Along the same lines, SyntaxError and TokenMissingError were improved to show a code snippet whenever possible:

$ elixir -e "hello + * world"
** (SyntaxError) nofile:1:9: syntax error before: '*'
  1 | hello + * world
    |         ^

Finally, new compilation tracers have been added, alongside a handful of functions in Module to retrieve module metadata, which can be used to enrich suggestions in programming environments.

Extended code formatting

The mix format task has been augmented with the notion of plugins. Plugins can teach the formatter how to format new files and how to format sigils, via the Mix.Tasks.Format behaviour.

For example, imagine that your project uses Markdown in two distinct ways: via a custom ~M sigil and via files with the .md and .markdown extensions. A custom plugin would look like this:

defmodule MixMarkdownFormatter do
  @behaviour Mix.Tasks.Format

  def features(_opts) do
    [sigils: [:M], extensions: [".md", ".markdown"]]

  def format(contents, opts) do
    # logic that formats markdown

Now any application can use your formatter as follows:

# .formatter.exs
  # Define the desired plugins
  plugins: [MixMarkdownFormatter],
  # Remember to update the inputs list to include the new extensions
  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}", "posts/*.{md,markdown}"]

Finally, the Code module has also been augmented with two functions: Code.string_to_quoted_with_comments/2 and Code.quoted_to_algebra/2. Those functions allow someone to retrieve the Elixir AST with their original source code comments, and then convert this AST to formatted code. In other words, those functions provide a wrapper around the Elixir Code Formatter, supporting developers who wish to create tools that directly manipulate and custom format Elixir source code.


1. Enhancements


  • [EEx] Add :parser_options to EEx functions


  • [Calendar] Add c:Calendar.year_of_era/3 to support calendars where the beginning of a new era does not align with the beginning of a new year
  • [CLI] Support --short-version on the CLI that does not boot the VM
  • [Code] Add Code.string_to_quoted_with_comments/2 and Code.quoted_to_algebra/2
  • [Code] Add more :token_metadata to aliases and remote calls when parsing strings
  • [Code] Add Code.Fragment module to provide best-effort information from code fragments. The module currently provides an updated Code.Fragment.cursor_context/2 with operator support and Code.Fragment.surround_context/2 which looks at a given position in a fragment and find its surrounding delimiters
  • [Code] Allow custom sigil formatting on Code.format_string!/2
  • [Code] Add {:on_module, bytecode, :none} trace to compilation tracers
  • [Enum] Optimize Enum.concat/1 for lists of lists
  • [Enum] Add Enum.slide/3
  • [Exception] Better format Elixir exceptions in Erlang
  • [Inspect] Allow default inspect fun to be set globally with Inspect.Opts.default_inspect_fun/1
  • [IO] Allow :eof to be given as limit to IO.getn/2
  • [Kernel] Support the :sigils option in import Mod, only: :sigils and allow the sigil modifiers to be also digits
  • [Kernel] Make get_in consistently abort when nil values are found
  • [Kernel] Improve compilation times by reducing the amount of copies of the AST across compiler processes
  • [Kernel] Raise if trying to define a module with a slash in its name
  • [Kernel] Warn when ?\ is used and there is no need for a escape character
  • [Kernel] Track structs in typespecs as export deps instead of compile-time deps
  • [Kernel] Add power operator (**/2)
  • [Keyword] Add Keyword.validate/2
  • [Keyword] Implement Keyword.filter/2 and Keyword.map/2
  • [List] Add List.keyfind!/3
  • [Macro] Add Macro.prewalker/1 and Macro.postwalker/1
  • [Macro.Env] Add the following reflection functions: required?/2, lookup_import/2, fetch_alias/2, and fetch_macro_alias/2
  • [Map] Implement Map.filter/2 and Map.map/2
  • [Module] Support :nillify_clauses in Module.get_definition/3
  • [Module] Add Module.attributes_in/1 and Module.overridables_in/1
  • [OptionParser] Add “did you mean?” suggestions to OptionParser.ParseError messages
  • [Record] Add record reflection via @__records__
  • [Task] Add Task.completed/1
  • [Task] Add Task.ignore/1 to keep a task running but ignoring all of its results
  • [Task] Reduce the amount of copying Task.async* functions
  • [URI] Add URI.new/1 and URI.new!/1


  • [ExUnit] Show hint if comparing different but equivalent strings
  • [ExUnit.CaptureIO] Add with_io/3 to return result with captured io
  • [ExUnit.CaptureLog] Add with_log/2 to return result with captured logs


  • [IEx.Autocomplete] Add path autocompletion whenever when the cursor follows "./ or "/ or "DRIVER: where DRIVER is a single letter
  • [IEx.Autocomplete] Add autocompletion for sigils, struct names, and struct fields
  • [IEx.Helpers] Allow multiple modules to be given to r/1


  • [Logger] Add Logger.put_application_level/2


  • [Mix] Add MIX_INSTALL_FORCE environment variable support
  • [Mix] Support :config and :system_env in Mix.install/2
  • [mix archive.install] Run loadconfig before building archive
  • [mix compile] Move Elixir version check to before deps are compiled, in order to give feedback earlier
  • [mix compile.elixir] Do not recompile files if their modification time change but their contents are still the same and the .beam files are still on disk
  • [mix compile.elixir] Do not recompile all Elixir sources when Erlang modules change, only dependent ones
  • [mix compile.elixir] Do not recompile Elixir files if mix.exs changes, instead recompile only files using Mix.Project or trigger a recompilation if a compiler option changes
  • [mix compile.elixir] Only recompile needed files when a dependency is added, updated or removed
  • [mix compile.elixir] Only recompile needed files when a dependency is configured
  • [mix deps] Add :subdir option to git deps
  • [mix escript.install] Run loadconfig before building escript
  • [mix format] Support :plugins in mix format that can hook into custom extensions and sigils
  • [mix format] Add Mix.Tasks.Format.formatter_for_file/2
  • [mix local.rebar] No longer support sub_dirs in Rebar 2 to help migration towards Rebar 3
  • [mix local.rebar] Support --if-missing option when installing Rebar
  • [mix local.rebar] Set REBAR_PROFILE=prod when compiling Rebar dependencies
  • [mix test] Support --profile-require=time to profile the time loading test files themselves
  • [mix test] Allow filtering modules from coverage using regex
  • [mix test] Allow the exit status of ExUnit to be configured and set the default to 2
  • [mix test] Exit with a status of 3 when coverage falls below threshold
  • [mix test] Write failed manifest when suite fails due to --warnings-as-errors
  • [mix test] Ignore MIX_TEST_PARTITION when partitions set to 1
  • [mix xref] Support multiple sinks and sources in mix xref graph
  • [mix xref] Add trace subcommand to print compilation dependencies between files
  • [mix xref] Add --fail-above option to mix xref
  • [mix xref] Add --label compile-connected to mix xref

2. Bug fixes


  • [EEx] Accept comments in EEx between do and the first clause
  • [EEx] Accept EEx expressions where -> is followed by newline


  • [Application] Warn if Application.compile_env or Application.compile_env! are called without a require
  • [Code] Make sure :static_atoms_encoder in Code.string_to_quoted/2 also applies to quoted keyword keys
  • [Code] Ensure bindings with no context are returned as atoms instead of {binding, nil} in eval operations
  • [Inspect] Fix a bug when inspecting a non-binary bitstring with colors
  • [Kernel] Raise if __CALLER__ or __ENV__ or __STACKTRACE__ are used in match
  • [Kernel] Improve error message on invalid argument for byte_size from binary concat
  • [Kernel] Raise when aliasing non-Elixir modules without :as
  • [Kernel] Allow unquote_splicing inside %{...} without parens
  • [Kernel] Ensure that waiting on a struct expansion inside a typespec is correctly tracked as waiting time in the compiler
  • [Kernel] Correctly parse the atom . as a keyword list key
  • [Kernel] Do not leak variables from the first generator in with and for special forms
  • [Kernel] Fix column number on strings with NFD characters
  • [Kernel] Fix a bug where a combination of dynamic line in quote with unquote of remote calls would emit invalid AST metadata
  • [OptionParser] Validate switch types/modifiers early on to give more precise feedback
  • [Protocol] Add defdelegate to the list of unallowed macros inside protocols as protocols do not allow function definitions
  • [Protocol] Warn if @callback, @macrocallback and @optional_callbacks are defined inside protocol
  • [Protocol] Ensure protocol metadata is deterministic on consolidation
  • [Range] Always show step when range is descending
  • [String] Update Unicode database to version 14.0
  • [URI] Only percent decode if followed by hex digits (according to URL Standard)
  • [Version] Ensure proper precedence of and/or in version requirements


  • [ExUnit] Fix formatter and counters from ExUnit.run/0 to consider all tests in a module whenever if a module’s setup_all fails
  • [ExUnit] Allow doctests newlines to be terminated by CRLF


  • [IEx] Fix the loss of .iex.exs context after a pry session


  • [Logger] Raise clear error message for invalid :compile_time_purge_matching configuration
  • [Logger] Fix a bug where Logger would not reset its discard counter under some scenarios


  • [mix compile.elixir] Recompile file if @external_resource is deleted
  • [mix compile.elixir] Print number of compiling files on all compiler cycles. This will make the Compiling N files (.ex) show up multiple times if necessary
  • [mix deps] Raise if local dep is unavailable while compiling
  • [mix deps.unlock] Fix blank output when dependency is not locked
  • [mix local.install] Do not respect MIX_DEPS_PATH for install commands
  • [mix release] Improve release scripts to make sure shell errors cascade by avoiding exporting and defining variables at once
  • [mix release] Do not boot release if RELEASE_COOKIE is empty
  • [mix release] Allow release running as a daemon to be restarted
  • [mix test] Allow coverage engine to also tag case, cond, and receive branches where the right side is a literal
  • [Mix.Shell] Add default option to Mix.Shell.yes?

3. Soft-deprecations (no warnings emitted)


  • [Code] Environment options in Code.eval_quoted/3 and Code.eval_string/3, such as :aliases and :tracers, have been deprecated in favor of passing an environment
  • [IO] :all on IO.getn is deprecated in favor of :eof
  • [URI] URI.parse/1 is deprecated in favor of URI.new/1 and URI.new!/1


  • [mix format] Mix.Tasks.Format.formatter_opts_for_file/2 is deprecated in favor of Mix.Tasks.Format.formatter_for_file/2

4. Hard-deprecations


  • [Code] Code.cursor_context/2 is deprecated, use Code.Fragment.cursor_context/2 instead
  • [Macro] Macro.to_string/2 is deprecated, use Macro.to_string/1 instead
  • [System] System.get_pid/0 is deprecated, use System.pid/0 instead
  • [Version] Using ! or != in version requirements is deprecated, use ~> or >= instead


  • [mix escript.build] :strip_beam option is deprecated in favor of :strip_beams
  • [Mix] :exit_code in Mix.raise/2 has been deprecated in favor of :exit_status
  • [Mix.Config] Mix.Config is deprecated in favor of Config module


  • Precompiled.zip SHA1: 5f6846da1f85c78500ee86240b412aec76c6fe77
  • Precompiled.zip SHA512: 10e5e40c6a1a3cd338538f4fb1e1fa6bfcce22157c1300b6779f27ba22b6ed8b1d5a60e0aa02efa6365c956f5181e4d9e80eb15b6137a03294f0e2b28fcc2391
  • Docs.zip SHA1: f7099c1646c8c5e8747e226452115c5f7e1d1a39
  • Docs.zip SHA512: 69af920c03e61c0310cc2964c66a332e2498dab62c1c314eeabff75617ab9fbe41c16124b41abbcd62bdae955d6f619cd8902336705dedd39686560c5186f05d

Have fun!


This is amazing! Waited for that for a very long time. Thank you!


I’m super excited about Code fragments.
Spending a day on iex will be even more pleasant.
Congrats on another nice release.
I’ll be sure testing this from tomorrow.


Amazing improvements! Makes life so much easier!

1 Like

Bada bing here we go :rocket:


That’s a great new addition!

And compilation improvements will definitely improve the developers productivity when working under a large codebase.

Kudos to the team!! Keep rocking!! :star_struck: :star_struck:

1 Like

Amazing, thank you!

1 Like

I’m SO EXCITED to see more effort being put into the code intelligence and tooling side of Elixir! Thanks so much to the contributors for making this happen!

1 Like

Great updates as always! :rocket:

I wonder if the support for formatter plugins is a prelude to heex formatting… :slight_smile:

1 Like

However, if you change the configuration of your application itself, the whole project is still recompiled.

@josevalim I think it will be clearer to mention mix.exs (as opposed to config/config.exs).

I am not sure I follow. mix.exs is already mentioned in its own bullet item and has different behavior. :slight_smile:

I think we should explicitly mention what are the file/s that it is referring to by “if you change the configuration of your application itself”. I thought it was mix.exs from the comments that appear at the end of that section.

To be clear, that means config :my_app, key: ... and so on.

No mention for this?? This is huge (if it is indeed what I think it is)! Thank you! :slight_smile:

I think it is what you think it is: