Elixir v1.12.0 released

Official announcement: Elixir v1.12 released - The Elixir programming language

Elixir v1.12 is out with improvements to scripting, tighter Erlang/OTP 24 integration, stepped ranges, and dozen of new functions across the standard library. Overall this is a small release, which continues our tradition of bringing Elixir developers quality of life improvements every 6 months.

Elixir v1.12 requires Erlang/OTP 22+. We also recommend running mix local.rebar after installation to upgrade to the latest Rebar versions, which includes support for Erlang OTP/24+.

Scripting improvements: Mix.install/2 and System.trap_signal/3

Elixir v1.12 brings new conveniences for those using Elixir for scripting (via .exs files). Elixir has been capable of managing dependencies for a quite long time, but it could only be done within Mix projects. In particular, the Elixir team is wary of global dependencies as any scripts that rely on system packages are brittle and hard to reproduce whenever your system changes.

Mix.install/2 is meant to be a sweetspot between single-file scripts and full-blown Mix projects. With Mix.install/2, you can list your dependencies on top of your scripts. When you execute the script for the first time, Elixir will download, compile, and cache your dependencies before running your script. Future invocations of the script will simply read the compiled artefacts from the cache:

IO.puts Jason.encode!(%{hello: :world})

Mix.install/2 also performs protocol consolidation, which gives script developers an option to execute their code in the most performant format possible.

Note: Mix.install/2 is currently experimental and it may change in future releases.

Another improvement to scripting is the ability to trap exit signals via System.trap_signal/3. All you need is the signal name and a callback that will be invoked when the signal triggers. For example, ExUnit leverages this functionality to print all currently running tests when you abort the test suite via SIGQUIT (Ctrl+\\ ):

$ mix test

Aborting test suite, the following have not completed:

* test query building [test/ecto/query_test.exs:48]
* test placeholders in Repo.insert_all [test/ecto/repo_test.exs:502]

Showing results so far...

78 doctests, 1042 tests, 0 failures

This is particularly useful when your tests get stuck and you want to know which one is the culprit.

Important: Trapping signals may have strong implications on how a system shuts down and behave in production and therefore it is extremely discouraged for libraries to set their own traps. Instead, they should redirect users to configure them themselves. The only cases where it is acceptable for libraries to set their own traps is when using Elixir in script mode, such as in .exs files and via Mix tasks.

Tighter Erlang/OTP 24 integration

Erlang/OTP 24 ships with JIT compilation support and Elixir developers don’t have to do anything to reap its benefits. There are many other features in Erlang/OTP 24 to look forwards to and Elixir v1.12 provides integration with many of them: such as support for 16bit floats in bitstrings as well as performance improvements in the compiler and during code evaluation.

Another excellent feature in Erlang/OTP 24 is the implementation of EEP 54, which provides extended error information for many functions in Erlang’s stdlib. Elixir v1.12 fully leverages this feature to improve reporting for errors coming from Erlang. For example, in earlier OTP versions, inserting an invalid argument into a ETS table that no longer exists would simply error with ArgumentError:

Interactive Elixir (1.11.0)
iex(1)> ets = :ets.new(:example, [])
iex(2)> :ets.delete(ets)
iex(3)> :ets.insert(ets, :should_be_a_tuple)
** (ArgumentError) argument error
    (stdlib 3.15) :ets.insert(#Reference<0.3845811859.2669281281.223553>, :should_be_a_tuple)

However, in Elixir v1.12 with Erlang/OTP 24:

Interactive Elixir (1.12.0)
iex(1)> ets = :ets.new(:example, [])
iex(2)> :ets.delete(ets)
iex(3)> :ets.insert(ets, :should_be_a_tuple)
** (ArgumentError) errors were found at the given arguments:

  * 1st argument: the table identifier does not refer to an existing ETS table
  * 2nd argument: not a tuple

    (stdlib 3.15) :ets.insert(#Reference<0.105641012.1058144260.76455>, :should_be_a_tuple)

Finally, note Rebar v2 no longer works on Erlang/OTP 24+. Mix defaults to Rebar v3 since v1.4, so no changes should be necessary by the huge majority of developers. However, if you are explicitly setting manager: :rebar in your dependency, you want to move to Rebar v3 by removing the :manager option. Support for unsupported Rebar versions will be removed from Mix in the future.

Stepped ranges

Elixir has support for ranges from before its v1.0 release. Ranges support only integers and are inclusive, using the mathematic notation a..b. Ranges in Elixir are either increasing 1..10 or decreasing 10..1 and the direction of the range was always inferred from the first and last positions. Ranges are always lazy as its values are emitted as they are enumerated rather than being computed upfront.

Unfortunately, due to this inference, it is not possible to have empty ranges. For example, if you want to create a list of n elements, you cannot express it with a range from 1..n, as 1..0 (for n=0) is a decreasing range with two elements.

Elixir v1.12 supports stepped ranges via the first..last//step notation. For example: 1..10//2 will emit the numbers 1, 3, 5, 7, and 9. You can consider the // operator as an equivalent to “range division”, as it effectively divides the number of elements in the range by step, rounding up on inexact scenarios. Steps can be either positive (increasing ranges) or negative (decreasing ranges). Stepped ranges bring more expressive power to Elixir ranges and they elegantly solve the empty range problem, as they allow the direction of the steps to be explicitly declared instead of inferred.

As of Elixir v1.12, implicitly decreasing ranges are soft-deprecated and warnings will be emitted in future Elixir versions based on our deprecation policy.

Additional functions

Elixir v1.12 has the additional of many functions across the standard library. The Enum module received additions such as Enum.count_until/2, Enum.product/1, Enum.zip_with/2, and more. The Integer module now includes Integer.pow/2 and Integer.extended_gcd/2. Finally, the Kernel module got two new functions, Kernel.then/2 and Kernel.tap/2, which are specially useful in |> pipelines.

v1.12.0 (2021-05-19)

1. Enhancements


  • [EEx.Engine] Add c:EEx.Engine.handle_text/3 callback that receives text metadata
  • [EEx.Engine] Emit warnings for unused “do” expression in EEx


  • [Code] Add Code.cursor_context/2 to return the context of a code snippet
  • [Code] Do not add newlines around interpolation on code formatting. Note this means formatted code that has interpolation after the line length on Elixir v1.12 won’t be considered as formatted on earlier Elixir versions
  • [Code] Do not add brackets when keywords is used in the access syntax
  • [Calendar] Support basic datetime format in Calendar.ISO parsing functions
  • [Code] Improve evaluation performance on systems running on Erlang/OTP 24+
  • [Date] Support steps via Date.range/3
  • [DateTime] Add offset to DateTime.to_iso8601/2 (now to_iso8601/3)
  • [Enum] Add Enum.count_until/2 and Enum.count_until/3
  • [Enum] Add Enum.product/1
  • [Enum] Add Enum.zip_with/2, Enum.zip_with/3, Enum.zip_reduce/3, and Enum.zip_reduce/4
  • [Enum] Add support for functions as the second argument of Enum.with_index/2
  • [Exception] Show error_info data for exceptions coming from Erlang
  • [Float] Add Float.pow/2
  • [Integer] Add Integer.pow/2 and Integer.extended_gcd/2
  • [IO] Add IO.stream/0 and IO.binstream/0 which default to STDIO with line orientation
  • [List] Add default value for List.first/1 and List.last/1
  • [Kernel] Add first..last//step as support for stepped ranges
  • [Kernel] Also warn for literal structs on min/2 and max/2
  • [Kernel] Add Kernel.tap/2 and Kernel.then/2
  • [Kernel] Do not add runtime dependencies to remotes in typespecs
  • [Kernel] When there is an unused variable warning and there is a variable with the same name previously defined, suggest the user may have wanted to use the pin operator
  • [Kernel] Improve error messages on invalid character right after a number
  • [Kernel] Show removal and deprecated tips from Erlang/OTP
  • [Macro] Add export dependencies on Macro.struct!/2
  • [Macro] Support :newline to customize newlines escaping in Macro.unescape_string/2
  • [Module] Raise on invalid @dialyzer attributes
  • [Module] Add Module.get_definition/2 and Module.delete_definition/2
  • [Module] Allow @on_load to be a private function
  • [Module] Validate @dialyzer related module attributes
  • [Module] Add Module.reserved_attributes/0 to list all reserved attributes by the language
  • [Range] Add Range.new/3 and Range.size/1
  • [Regex] Add offset option to Regex.scan/3 and Regex.run/3
  • [Registry] Support :compression on Registry tables
  • [Registry] Support Registry.values/3 for reading values under a given key-pid pair
  • [Stream] Add Stream.zip_with/2 and Stream.zip_with/3
  • [String] Add :turkic mode option to String case functions
  • [String] Update to Unicode 13.0
  • [System] Add System.trap_signal/3 and System.untrap_signal/2
  • [System] Add System.shell/2 to invoke a command that is interpreted by the shell
  • [Tuple] Add Tuple.sum/1 and Tuple.product/1
  • [URI] Support RFC3986 compliant encoding and decoding of queries via the :rfc3986 option


  • [ExUnit] Intercept SIGQUIT (via Ctrl+\) and show a list of all aborted tests as well as intermediate test results
  • [ExUnit] Interpolate module attributes in match assertions diffs
  • [ExUnit] Print how much time is spent on async vs sync tests
  • [ExUnit] Improve error messages for doctests
  • [ExUnit] Compile doctests faster (often by two times)
  • [ExUnit] Add ExUnit.async_run/0 and ExUnit.await_run/1


  • [IEx] Make IEx’ parser configurable to allow special commands
  • [IEx] Show function signature when pressing tab after the opening parens of a function
  • [IEx] If an IEx expression starts with a binary operator, such as |>, automatically pipe in the result of the last expression


  • [Mix] Add Mix.install/2 for dynamically installing a list of dependencies
  • [Mix] Support :exit_code option in Mix.raise/2
  • [Mix] Discard MIX_ENV and MIX_TARGET values if they are empty strings
  • [Mix] Print the time taken to execute a task with on MIX_DEBUG=1
  • [mix compile.erlang] Compile multiple files in parallel
  • [mix escript.build] Deep merge configuration and ensure argv is set when executing config/runtime.exs
  • [mix release] Add RELEASE_PROG to releases with the name of the executable starting the release
  • [mix release] Support remote.vm.args to customize how the connecting VM boots
  • [mix test] Run all available tests if there are no pending --failed tests. This provides a better workflow as you no longer need to toggle the --failed flag between runs

2. Bug fixes


  • [CLI] Ensure -e "" (with an empty string) parses correctly on Windows
  • [Inspect] Do not override user supplied :limit option for derived implementations
  • [Kernel] Allow heredoc inside a heredoc interpolation
  • [Kernel] Preserve CRLF on heredocs
  • [Kernel] Public functions without documentation now appear as an empty map on Code.fetch_docs/1, unless they start with underscore, where they remain as :none. This aligns Elixir’s implementation with EEP48
  • [Kernel] Do not crash when complex literals (binaries and maps) are used in guards
  • [Kernel] Properly parse keywords (such as end) followed by the :: operator
  • [Kernel] Do not ignore unimplemented signatures from generated functions
  • [Kernel] Improve error message when an expression follows a keyword list without brackets
  • [Macro] Macro.decompose_call/1 now also consider tuples with more than 2 elements to not be valid calls
  • [Macro] Fix Macro.to_string/1 double-escaping of escape characters in sigils
  • [Macro] Fix Macro.underscore/1 on digits preceded by capitals: “FOO10” now becomes “foo10” instead of “fo_o10”
  • [Macro] Preserve underscores between digits on Macro.underscore/1
  • [OptionParser] Properly parse when numbers follow-up aliases, for example, -ab3 is now parsed as -a -b 3
  • [Path] Fix Path.relative_to/2 when referencing self
  • [Path] Do not crash when a volume is given to Path.absname/1, such as “c:”
  • [Task] Ensure Task.async_stream/2 with ordered: false discard results as they are emitted, instead of needlessly accumulating inside the stream manager
  • [Task] Raise if :max_concurrency is set to 0 on streaming operations
  • [URI] Do not discard empty paths on URI.merge/2


  • [ExUnit.Case] Make @tag tmp_dir an absolute directory, avoiding inconsistencies if the test changes the current working directory
  • [ExUnit.Diff] Fix cases where the diffing algorithm would fail to print a pattern correct


  • [IEx] Fix auto-completion inside remote shells


  • [mix app.config] Do not emit false positive warnings when configured dependencies that have runtime: false set
  • [mix compile.elixir] Ensure that a manifest is generated even with no source code
  • [mix compile.elixir] Make sure export dependencies trigger recompilation when the dependency is removed as well as when the whole file is removed
  • [mix compile.elixir] Do not emit false positive warnings when a path dependency adds a module that is then used by the current application in the same mix compile cycle
  • [mix test] Ensure protocols within the current project are consolidated when --cover is given
  • [mix release] Improve compliance of release scripts with stripped down Linux installations
  • [mix release] Preserve file mode when copying non-beam ebin files
  • [mix xref] Ensure args are passed to the underlying mix compile call

3. Soft-deprecations (no warnings emitted)


  • [Kernel] Using first..last to match on ranges is soft-deprecated and will warn on future Elixir versions. Use first..last//step instead
  • [Kernel] Using first..last to create decreasing ranges is soft-deprecated and will warn on future versions. Use first..last//-1 instead

4. Hard-deprecations


  • [EEx.Engine] use EEx.Engine is deprecated in favor of explicit delegation


  • [Kernel] The binary operator ^^^ is deprecated. If you are using Bitwise.^^^/2, use Bitwise.bxor/2 instead
  • [Kernel] Deprecate @foo() in favor of @foo
  • [System] Deprecate System.stacktrace/0 (it was already deprecated outside of catch/rescue and now it is deprecated everywhere)


  • [mix compile] The :xref compiler is deprecated and it has no effect. Please remove it from your mix.exs file.


  • Precompiled.zip SHA1: b607b2d0e78e1ae6f9d112ba3e1b617a1ee7580b
  • Precompiled.zip SHA512: 57e970640f7e273a62fbde60545ed85c18d667e194d0d3483b941ea3164f12664cc0c186968c1f341253f1907157ae88953b5caa413204f93bba08710fdc0b50
  • Docs.zip SHA1: fbf8939ea56f3cdda90ee04680fdc43f7b1d41e2
  • Docs.zip SHA512: c06ee0a72cbb4cc138a11b1acee14efde2cc2c7de5a121ee386c9a9ba583ccc10dd8b5ebc29cbf89bd9da8c091868d8fdd4b148bfa6fa564dc033449700d0b08

Have fun!


Lots of goodies in this release. Thanks Jose & contributors!


Lots of amazing things in this release, thank you Jose and & Team


Super excited to get onto 1.12 and OTP 24. Great work @josevalim and the rest of the Elixir team!


9 posts were split to a new topic: Using Rustler with OTP24

Chocolatey still has the older version 1.11.2 Chocolatey Software | Elixir 1.11.2

Any ETA on Chocolatey availability?

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There is a link to contact the maintainers there: Chocolatey Software

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Does anybody know what is the difference between installing with asdf releases 1.12.0 and 1.12.0-otp-24 ?

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I love how the JIT is the same that gzdoom uses, lol. ^.^

Elixir 1.12 is pretty nice, been running it’s beta and RC’s for a bit now locally in an asdf area. ^.^

The default 1.12.0 elixir is compiled with support for the lowest level of supported otp version, so it will work with any OTP of that version or higher, but might be missing some optimizations. The 1.12.0-otp-24 is built with otp-24 as the base level version, meaning it will only run on otp-24 or higher, but has more optimizations that it might not have otherwise had.


Thank you for the explanation

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We will do a patch release soon, v1.12.1, to address some warnings and a regression in Macro.camelize. If you haven’t tried out v1.12.0 yet, please do so, and let us know if you see any unexpected behaviour!


Hey :wave:
We just tried to upgrade Elixir from 1.11.3 to 1.12.0, while sticking to OTP 23.2.3 for now.

We got some warnings for our behaviours:
@behaviour MyApp.Some.Behaviour does not exist (in module MyApp.Some.Module.UsingBehaviour) & warning: got "MyApp.Some.Behaviour" for function some_function/1 but this behaviour does not specify such callback. There are no known callbacks, please specify the proper @behaviour and make sure it defines callbacks

Some time ago, we saw similar errors when defining mocks for behaviours. There we used Code.ensure_compiled(MyApp.Some.Behaviour) for the “missing” behaviour. But as it is now complaining about the use of behaviours in several modules, putting a Code.ensure_compiled/1 at the top doesn’t feel right.

Does anyone have an idea where this might be coming from?


Thanks @woolfred! We were not expecting changes on this area, so it should work. Unfortunately, we would also need a mechanism to reproduce, as it only happens under certain scenarios (such as cyclic dependencies). I appreciate you giving it a try!

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Looks like a great release! Looking forward to using mix scripts more!

A question though, I am maintaining a tool used at Exercism (www.exercism.io) to help teach Elixir fluency. We are using an isolated docker container (no network, read only, unprivileged user) to run tests on untrusted student code (via mix test) and using a custom ExUnit Formatter to capture test-run output in a certain format. To keep the requirements for students simple, we have been injecting the compiled assets of our ExUnit formatter into the compiled assets (_build/test/lib/<project>/ebin) of the solution, which we then use with the mix test --formatter CustomFormatter command line option.

Prior to 1.11 we added our assets to the consolidated dir for this to work, and then with 1.11 it stopped working until we added them to the ebin dir.

With 1.12, this seems to have changed again and now ExUnit is not using our custom formatter despite the assets being present in the ebin directory. I realize this isn’t a typical way to sideload a module into a compiled app.

Is there a way to accomplish this side-loading in 1.12? Or should we explore another method?

Because of the security concerns or potential abuse from bad actors, an exercise must be able to compile/load in an isolated container (no network, read only, unprivileged user).

You should be able to do this:

elixir -pa my-ebin-with-formatter -S mix test

Elixir v1.12.1 is out addressing some of the reported regressions. Thanks!


This is awesome. I think I’m going to love then/2 and tap/2. Can’t wait to explore 1.12 more

Thanks @josevalim! That suggestion to use -pa worked like magic!

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