View Source Changelog for Elixir v1.18

TODO.

Type system improvements

ExUnit improvements

ExUnit now supports parameterized tests to run the same test module multiple times under different parameters.

For example, Elixir ships a local, decentralized and scalable key-value process storage called Registry. The registry can be partitioned and its implementation differs depending if partitioning is enabled or not. Therefore, during tests, we want to ensure both modes are exercised. With Elixir v1.18, we can achieve this by writing:

defmodule Registry.Test do
  use ExUnit.Case,
    async: true,
    parameterize: [
      %{partitions: 1},
      %{partitions: 8}
    ]

  # ... the actual tests ...
end

ExUnit parameterizes whole test modules. If your modules are configured to run concurrently, as above, so will the parameterized ones.

ExUnit also comes with the ability of specifying test groups. While ExUnit supports running tests concurrently, those tests must not have shared state between them. However, in large applications, it may be common for some tests to depend on some shared state, and other tests to depend on a completely separate state. For example, part of your tests may depend on Cassandra, while others depend on Redis. Prior to Elixir v1.18, these tests could not run concurrently, but in v1.18 they might as long as they are assigned to different groups. Tests modules within the same group do not run concurrently, but across groups, they might.

With features like async tests, suite partitioning, and now grouping, Elixir developers have plenty of flexibility to make the most use of their machine resources, both in development and in CI.

mix format --migrate

TODO.

Potential incompatibilities

This release no longer supports WERL (a graphical user interface on Windows used by Erlang 25 and earlier). For a better user experience on Windows terminals, use Erlang/OTP 26+.

Furthermore, in order to support inference of patterns, Elixir will raise if it finds recursive variable definitions. This means patterns that never match, such as this one, will no longer compile:

def foo(x = {:ok, y}, x = y)

However, recursion of root variables (where variables directly point to each other), will also fail to compile:

def foo(x = y, y = z, z = x)

While the definition above could succeed (as long as all three arguments are equal), the cycle is not necessary and could be removed, as below:

def foo(x = y, y = z, z)

You may also prefer to write using guards:

def foo(x, y, z) when x == y and y == z

v1.18.0-dev

1. Enhancements

Elixir

  • [CLI] Add experimental PowerShell scripts for elixir, elixirc, and mix on Windows. Those provide a safer entry point for running Elixir from other platforms
  • [Code] Support several migration options in Code.format_string!/2
  • [Code] Add parenthesis around -- and --- in Code.format_string!/2 to make precedence clearer
  • [Code.Fragment] Have :capture_arg as its own entry in Code.Fragment.surround_context/2
  • [Config] Add Config.read_config/1
  • [Enumerable] Add Enum.product_by/2 and Enum.sum_by/2
  • [Exception] Add MissingApplicationsError exception to denote missing applications
  • [Kernel] Update source code parsing to match UTS #55 latest recommendations. In particular, mixed script is allowed in identifiers as long as they are separate by underscores (_), such as http_сервер. Previously allowed highly restrictive identifiers, which mixed Latin and other scripts, such as the japanese word for t-shirt, Tシャツ, now require the underscore as well
  • [Kernel] Warn on bidirectional confusability in identifiers
  • [Kernel] Now verify the type of the binary generators
  • [Kernel] Track the type of tuples in patterns and inside elem/2
  • [List] Add List.ends_with?/2
  • [Macro] Improve dbg handling of if/2, with/1 and of code blocks
  • [Macro] Add Macro.struct_info!/2 to return struct information mirroring mod.__info__(:struct)
  • [Process] Handle arbitrarily high integer values in Process.sleep/1
  • [String] Inspect special whitespace and zero-width characters using their Unicode representation

ExUnit

  • [ExUnit] Support parameterized tests on ExUnit.Case
  • [ExUnit] Support test groups: tests in the same group never run concurrently

IEx

  • [IEx] Add :dot_iex support to IEx.configure/1
  • [IEx] Add report for normal/shutdown exits in IEx

Mix

  • [mix compile] Ensure only a single operating system process can compile at a given time
  • [mix deps.get] Ensure only a single operating system process can fetch deps at a given time
  • [mix format] Add mix format --migrate to migrate from deprecated functionality
  • [mix test] Taint failure manifest if requiring or compiling tests fail
  • [Mix.Project] Add a :listeners configuration to listen to compilation events from the current and other operating system processes
  • [Mix.Task.Compiler] Add API for fetching all persisted compiler diagnostics
  • [Mix.Task.Compiler] Add API for fetching all compiler tasks

2. Bug fixes

Elixir

  • [Code.Fragment] Properly handle keyword keys as their own entry
  • [Inspect.Algebra] Ensure next_break_fits respects line_length
  • [Module] Include module attribute line and name when tracing its aliases

ExUnit

  • [ExUnit.Assertions] Raise if guards are used in assert/1 with =

IEx

Mix

  • [mix compile] Ensure warnings from external resources are emitted with --all-warnings when files do not change
  • [mix deps.compile] Fix escaping issues when invoking rebar3 in some cases
  • [mix escript] Fix escript layout and support storing priv directories
  • [mix release] Make .app files deterministic in releases

3. Soft deprecations (no warnings emitted)

Elixir

  • [Inspect.Algebra] color/3 is deprecated in favor of color_doc/3
  • [Inspect.Algebra] fold_doc/2 is deprecated in favor of fold/2
  • [Kernel] Deprecate unless in favor of if. Use mix format --migrate to automate the migration
  • [Macro] Macro.struct!/2 is deprecated in favor of Macro.struct_info!/2

4. Hard deprecations

EEx

  • [EEx] <%# is deprecated in favor of <%!-- or <% #
  • [EEx] c:EEx.handle_text/2 is deprecated in favor of c:EEx.handle_text/3

Elixir

Mix

  • [mix cmd] Deprecate mix cmd --app APP in favor of mix do --app APP
  • [Mix.Tasks.Compile] Deprecate compilers/0 in favor of Mix.Task.Compiler.compilers/0

v1.17

The CHANGELOG for v1.17 releases can be found in the v1.17 branch.