v1.15.0-rc.0

This release requires Erlang/OTP 24 and later.

Elixir v1.15 is a smaller release with focused improvements
on compilation and boot times. This release also completes
our integration process with Erlang/OTP logger, bringing new
features such as log rotation and compaction out of the box.

You will also find additional convenience functions in Code,
Map, Keyword, all Calendar modules, and others.

Compile and boot-time improvements

The last several releases brought improvements to compilation
time and this version is no different. In particular, Elixir
now caches and prunes load paths before compilation, ensuring your
project (and dependencies!) compile faster and in an environment
closer to production.

In a nutshell the Erlang VM loads modules from code paths. Each
application that ships with Erlang and Elixir plus each dependency
become an entry in your code path. The larger the code path, the
more work Erlang has to do in order to find a module.

In previous versions, Mix would only add entries to the load paths.
Therefore, if you compiled 20 dependencies and you went to compile
the 21st, the code path would have 21 entries (plus all Erlang and
Elixir apps). This allowed modules from unrelated dependencies to
be seen and made compilation slower the more dependencies you had.
With this release, we will now prune the code paths to only the ones
listed as dependencies, bringing the behaviour closer to mix release.

Furthermore, Erlang/OTP 26 allows us to start applications
concurrently and cache the code path lookups, decreasing the cost of
booting applications. The combination of Elixir v1.15 and Erlang/OTP 26
should reduce the boot time of applications, such as when starting
iex -S mix or running a single test with mix test, from 5% to 30%.

The compiler is also smarter in several ways: @behaviour declarations
no longer add compile-time dependencies and aliases in patterns and
guards add no dependency whatsoever, as no dispatching happens. Furthermore,
Mix now tracks the digests of @external_resource files, reducing the
amount of recompilation when swapping branches. Finally, dependencies
are automatically recompiled when their compile-time configuration changes.

Potential incompatibilities

Due to the code path pruning, if you have an application or dependency
that does not specify its dependencies on Erlang and Elixir application,
it may no longer compile successfully in Elixir v1.15. You can temporarily
disable code path pruning by setting prune_code_paths: false in your
mix.exs, although doing so may lead to runtime bugs that are only
manifested inside a mix release.

Compiler warnings and errors

The Elixir compiler can now emit many errors for a single file, making
sure more feedback is reported to developers before compilation is aborted.

In Elixir v1.14, an undefined function would be reported as:

** (CompileError) undefined function foo/0 (there is no such import)
    my_file.exs:1

In Elixir v1.15, the new reports will look like:

error: undefined function foo/0 (there is no such import)
  my_file.exs:1

** (CompileError) nofile: cannot compile file (errors have been logged)

A new function, called Code.with_diagnostics/2, has been added so this
information can be leveraged by editors, allowing them to point to several
errors at once.

Integration with Erlang/OTP logger

This release provides additional features such as global logger
metadata and file logging (with rotation and compaction) out-of-the-box!

This release also soft-deprecates Elixir's Logger Backends in
favor of Erlang's Logger handlers. Elixir will automatically
convert your :console backend configuration into the new
configuration. Previously, you would set:

config :logger, :console,
  level: :error,
  format: "$time $message $metadata"

Which is now translated to the equivalent:

config :logger, :default_handler,
  level: :error

config :logger, :default_formatter,
  format: "$time $message $metadata"

If you use Logger.Backends.Console or other backends, they are
still fully supported and functional. If you implement your own
backends, you want to consider migrating to
:logger_backends
in the long term.

See the new Logger documentation for more information on the
new features and on compatibility.

v1.15.0-rc.0 (2022-05-22)

1. Enhancements

EEx

• [EEx] Include source code snippets in syntax errors

Elixir

• [Calendar] Add support for epoch time (%s) to Calendar.strftime/2
• [Code] Code.format_string!/2 now converts 'charlists' into ~c"charlists" by default
• [Code] Add :on_undefined_variable to the compiler options to preserve the warning behaviour which was deprecated back in Elixir v1.4
• [Code] Add Code.loaded?/1 and Code.ensure_all_loaded(!)/1
• [Code] Add Code.prepend_paths/1, Code.append_paths/1, and Code.delete_paths/1
• [Code] Add Code.with_diagnostics/2 to return diagnostics when compiling and evaluating code
• [Code.Fragment] Support nested expressions in Code.Fragment.cursor_context/1
• [Code.Fragment] Keep operators and no paren calls in Code.Fragment.container_cursor_to_quoted/1
• [Date] Add Date.before?/2 and Date.after?/2
• [DateTime] Add DateTime.before?/2 and DateTime.after?/2
• [DateTime] Support precision in DateTime.utc_now/2
• [Inspect] Inspect now renders 'charlists' as ~c"charlists" by default
• [Kernel] Break down case and cond inside dbg/2
• [Kernel] Add t:nonempty_binary/0 and t:nonempty_bitstring/0
• [Kernel] Treat @behaviours as runtime dependencies
• [Kernel] Do not add runtime dependencies for alias references in patterns and guards
• [Kernel] Warn for nested calls without parens inside keywords
• [Kernel] Support for multi-letter uppercase sigils
• [Kernel] Introduce mechanism to collect several errors in a module. Previously, as soon as there was a compilation error, compilation would fail. Now the compiler became a bit smarter and will report multiple errors whenever possible as multiple error: ... messages, similar to warning: ...
• [Kernel.CLI] Support --sname undefined/--name undefined so a name is automatically generated
• [Keyword] Add Keyword.split_with/2
• [Macro] Improve error message when piping into an expression ending in bracket-based access
• [Macro.Env] Add Macro.Env.lookup_alias_as/2
• [Map] Add Map.split_with/2
• [Map] Add Map.intersect/2 and Map.intersect/3
• [MapSet] Add MapSet.split_with/2
• [MapSet] Optimize most functions
• [NaiveDateTime] Add NaiveDateTime.beginning_of_day/1 and NaiveDateTime.end_of_day/1
• [NaiveDateTime] Add NaiveDateTime.before?/2 and NaiveDateTime.after?/2
• [NaiveDateTime] Support precision in NaiveDateTime.utc_now/2
• [OptionParser] Support :return_separator option
• [Process] Add Process.alias/0,1 and Process.unalias/1
• [Range] Add Range.split/2
• [String] Update Unicode to version 15.0.0
• [String] Add :fast_ascii mode to String.valid?/2
• [Supervisor] Add support for automatic shutdown in Supervisor
• [System] Support :lines in System.cmd/3 to capture output line by line
• [Task] Remove head of line blocking on Task.yield_many/2
• [Task] Enable selective receive optimizations in Erlang/OTP 26+
• [Task.Supervisor] Do not copy args on temporary Task.Supervisor.start_child/2
• [Time] Add Time.before?/2 and Time.after?/2
• [URI] Add URI.append_path/2

ExUnit

• [ExUnit] Add more color configuration to ExUnit CLI formatter
• [ExUnit.Callbacks] Accept {module, function} tuples in ExUnit setup callbacks
• [ExUnit.Doctest] Add ExUnit.DocTest.doctest_file/2
• [ExUnit.Formatter] When comparing two anonymous functions, defined at the same place but capturing a different environment, we will now also diff the environments

IEx

• [IEx] Make pry opt-in on dbg with --dbg pry
• [IEX] Support IEX_HOME
• [IEx.Autocomplete] Only provide aliases when autocompleting alias, import, and require
• [IEx.Autocomplete] Provide field completion on map and struct updates
• [IEx.Helpers] Add runtime_info(:allocators)
• [IEx.Info] Implement protocol for Range, DateTime, and Regex

Logger

• [Logger] Add Logger.add_handlers/1 and Logger.default_formatter/1
• [Logger] Introduce default_formatter and default_handler configuration for Logger which configures Erlang/OTP logger
• [Logger] Add :always_evaluate_messages configuration to Logger
• [Logger.Formatter] Implement the Erlang Logger formatter API
• [Logger.Formatter] Add support for ports in Logger metadata

Mix

• [mix app.start] Allow applications to be started concurrently via the :start_concurrently configuration
• [mix compile] Set --all-warnings by default
• [mix compile] Reduce the amount of filesystem lookups for path dependencies by storing timestamps in manifests
• [mix compile] Track digests of @external_resources
• [mix compile.app] Write optional_applications to .app file
• [mix compile.elixir] Add --purge-consolidation-path-if-stale which will purge the given consolidation path if compilation is required
• [mix deps.compile] Automatically recompile dependencies if their compile env changes
• [mix deps.get] Automatically install Hex and Rebar on mix deps.get/mix deps.update
• [mix deps.get] Support --check-locked which raises if changes to the lockfile are required
• [mix eval] Allow passing additional arguments
• [mix format] Support --no-exit option
• [mix format] Allow multiple formatters per file extension and sigil
• [mix...

v1.14.5

This release contains fixes for Erlang/OTP 26.

Bug fixes

Elixir

• [CLI] Fix a bug where stdout would block when there was no attached terminal on Windows when running on Erlang/OTP 26

Mix

• [Mix] Properly set SSL configuration for Mix downloads when running on Erlang/OTP 26

v1.14.4

This release adds basic support for Erlang/OTP 26. When migrating
to Erlang/OTP 26, keep it mind it changes how maps are stored
internally and they will be printed and traversed in a different
order (note maps never provided a guarantee of their order).
To aid migration, this release adds :sort_maps to inspect
custom options, in case you want to sort them before inspection:

inspect(map, custom_options: [sort_maps: true])

Enhancements

Elixir

• [Inspect] Add :sort_maps to Inspect.Opts.custom_options

IEx

• [IEx] Support shell history in Erlang/OTP 26+

Mix

• [mix compile.elixir] Optimize application tracer

Bug fixes

Elixir

• [Code] Properly handle blocks with comments in all cases in Code.quoted_to_string_with_comments/2
• [Kernel] Fix debug_info/4 when returning core_v1
• [Kernel] Store complete path on quote keep: true to avoid invalid stacktraces
• [Kernel] Fix column count when tokenizing escaped interpolations
• [Stream] Fix Stream.zip/1 hanging on empty list

Mix

• [mix format] Don't call formatter on directories

v1.14.3

1. Enhancements

Elixir

• [Kernel] Speed up loading of runtime modules in the parallel compiler
• [Range] Optimize range membership implementation

ExUnit

• [ExUnit] Return values from running doctests and make their order consistent

2. Bug fixes

Elixir

• [Calendar] Fix handling of negative years in Calendar.strftime/2
• [Exception] Improve blaming of FunctionClauseError with is_struct/2 guards
• [Kernel] Fix invalid variable scoping in defguard expansion
• [Kernel] Do not warn on captured underscored vars from defmodule
• [Kernel] Do not crash for missing line info on type warnings
• [Macro] Fix Macro.to_string/1 for large negative integers
• [Macro] Properly type and escape expansion of __ENV__ in macros
• [Path] Make sure Path.wildcard/2 expands .. symlinks accordingly
• [Range] Address corner cases in Range.disjoint?/2 implementation

ExUnit

• [ExUnit.DocTest] Remove unnecessary literal quotes from error message on reports

v1.14.2

1. Enhancements

Elixir

• [Code] Add Code.eval_quoted_with_env/4 with support for the :prune_binding option

ExUnit

• [ExUnit.Case] Allow test cases to not be registered on use
• [ExUnit.DocTest] Include :doctest and :doctest_line as meta tags
• [ExUnit.Formatter] Expose ExUnit.Formatter.format_assertion_diff/4

Mix

• [Mix] Mix.install/2 accepts atoms as paths

2. Bug fixes

Elixir

• [Code.Formatter] Fix size*unit shortcut in bitstring
• [Kernel] Generate unique variables for macro expansion of defguard
• [Protocol] Expand :for in protocols with the appropriate env

ExUnit

• [ExUnit] Do not run duplicate cases on ExUnit.run/1

Mix

• [mix test] Ensure proper error message when there is no test directory

v1.14.1

1. Enhancements

Elixir

• [Kernel] Perform partial expansion of literals in module attributes
• [Kernel] Do not add compile-time dependencies for literals as defaults in Application.compile_env/3 inside module attributes
• [Macro] Add Macro.expand_literals/2 and Macro.expand_literals/3
• [System] Add :close_stdin to System.shell/2

Mix

• [mix test] Accept --all-warnings option

2. Bug fixes

Elixir

• [Kernel] Fix misleading warning when :uniq is given in for comprehensions and the result is unused
• [Kernel] Improve error message for when there is a conflicting struct and ignoring module conflict
• [Kernel] Do not delete @enforce_keys attribute after defstruct declaration
• [Kernel] Do not crash the checker on modules with missing :debug_info chunk
• [Macro] Fix error in Macro.to_string/2 when converting an AST with :erlang.binary_to_atom/2
• [String] Fix String.split/3 and String.next_grapheme/1 returning invalid results on invalid UTF-8 encoding
• [System] Do not close stdin by default in System.shell/2
• [URI] Do not return uri.port as :undefined in certain cases in URI.new/1

ExUnit

• [ExUnit.DocTest] Do not crash when both :moduledoc and functions are specified in :only

IEx

• [CLI] Fix invalid argument handling when --no-pry is given

Mix

• [mix format] Do not cache inputs from .formatter.exs so they are properly re-evaluted on every call

v1.14.0

Elixir v1.14 brings many improvements to the debugging experience in Elixir
and data-type inspection. It also includes a new abstraction for easy
partitioning of processes called PartitionSupervisor, as well as improved
compilation times and error messages.

Elixir v1.14 is the last version to support Erlang/OTP 23. Consider updating
to Erlang/OTP 24 or Erlang/OTP 25.

dbg

Kernel.dbg/2 is a new macro that's somewhat similar to IO.inspect/2, but
specifically tailored for debugging.

When called, it prints the value of whatever you pass to it, plus the debugged
code itself as well as its location. This code:

# In my_file.exs
feature = %{name: :dbg, inspiration: "Rust"}
dbg(feature)
dbg(Map.put(feature, :in_version, "1.14.0"))

Prints this:

$ elixir my_file.exs
[my_file.exs:2: (file)]
feature #=> %{inspiration: "Rust", name: :dbg}

[my_file.exs:3: (file)]
Map.put(feature, :in_version, "1.14.0") #=> %{in_version: "1.14.0", inspiration: "Rust", name: :dbg}

dbg/2 can do more. It's a macro, so it understands Elixir code. You can see
that when you pass a series of |> pipes to it. dbg/2 will print the value
for every step of the pipeline. This code:

# In dbg_pipes.exs
__ENV__.file
|> String.split("/", trim: true)
|> List.last()
|> File.exists?()
|> dbg()

Prints this:

$ elixir dbg_pipes.exs
[dbg_pipes.exs:5: (file)]
__ENV__.file #=> "/home/myuser/dbg_pipes.exs"
|> String.split("/", trim: true) #=> ["home", "myuser", "dbg_pipes.exs"]
|> List.last() #=> "dbg_pipes.exs"
|> File.exists?() #=> true

IEx and Prying

dbg/2 supports configurable backends. IEx automatically replaces the default
backend by one that halts the code execution with IEx.Pry, giving developers
the option to access local variables, imports, and more. This also works with
pipelines: if you pass a series of |> pipe calls to dbg (or pipe into it at the
end, like |> dbg()), you'll be able to step through every line in the pipeline.

You can keep the default behaviour by passing the --no-pry option to IEx.

PartitionSupervisor

PartitionSupervisor is a new module that implements a new supervisor type. The
partition supervisor is designed to help with situations where you have a single
supervised process that becomes a bottleneck. If that process's state can be
easily partitioned, then you can use PartitionSupervisor to supervise multiple
isolated copies of that process running concurrently, each assigned its own
partition.

For example, imagine you have an ErrorReporter process that you use to report
errors to a monitoring service.

# Application supervisor:
children = [
  # ...,
  ErrorReporter
]

Supervisor.start_link(children, strategy: :one_for_one)

As the concurrency of your application goes up, the ErrorReporter process
might receive requests from many other processes and eventually become a
bottleneck. In a case like this, it could help to spin up multiple copies of the
ErrorReporter process under a PartitionSupervisor.

# Application supervisor
children = [
  {PartitionSupervisor, child_spec: ErrorReporter, name: Reporters}
]

The PartitionSupervisor will spin up a number of processes equal to
System.schedulers_online() by default (most often one per core). Now, when
routing requests to ErrorReporter processes we can use a :via tuple and
route the requests through the partition supervisor.

partitioning_key = self()
ErrorReporter.report({:via, PartitionSupervisor, {Reporters, partitioning_key}}, error)

Using self() as the partitioning key here means that the same process will
always report errors to the same ErrorReporter process, ensuring a form of
back-pressure. You can use any term as the partitioning key.

A Common Example

A common and practical example of a good use case for PartitionSupervisor is
partitioning something like a DynamicSupervisor. When starting many processes
under it, a dynamic supervisor can be a bottleneck, especially if said processes
take a long time to initialize. Instead of starting a single DynamicSupervisor,
you can start multiple:

children = [
  {PartitionSupervisor, child_spec: DynamicSupervisor, name: MyApp.DynamicSupervisors}
]

Supervisor.start_link(children, strategy: :one_for_one)

Now you start processes on the dynamic supervisor for the right partition.
For instance, you can partition by PID, like in the previous example:

DynamicSupervisor.start_child(
  {:via, PartitionSupervisor, {MyApp.DynamicSupervisors, self()}},
  my_child_specification
)

Improved errors on binaries and evaluation

Erlang/OTP 25 improved errors on binary construction and evaluation. These improvements
apply to Elixir as well. Before v1.14, errors when constructing binaries would
often be hard-to-debug generic "argument errors". With Erlang/OTP 25 and Elixir v1.14,
more detail is provided for easier debugging. This work is part of EEP
54.

Before:

int = 1
bin = "foo"
int <> bin
#=> ** (ArgumentError) argument error

Now:

int = 1
bin = "foo"
int <> bin
#=> ** (ArgumentError) construction of binary failed:
#=>    segment 1 of type 'binary':
#=>    expected a binary but got: 1

Slicing with steps

Elixir v1.12 introduced stepped ranges, which are ranges where you can
specify the "step":

Enum.to_list(1..10//3)
#=> [1, 4, 7, 10]

Stepped ranges are particularly useful for numerical operations involving
vectors and matrices (see Nx, for example).
However, the Elixir standard library was not making use of stepped ranges in its
APIs. Elixir v1.14 starts to take advantage of steps with support for stepped
ranges in a couple of functions. One of them is Enum.slice/2:

letters = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"]
Enum.slice(letters, 0..5//2)
#=> ["a", "c", "e"]

binary_slice/2 (and binary_slice/3 for completeness) has been added to the
Kernel module, that works with bytes and also support stepped ranges:

binary_slice("Elixir", 1..5//2)
#=> "lxr"

Expression-based inspection and Inspect improvements

In Elixir, it's conventional to implement the Inspect protocol for opaque
structs so that they're inspected with a special notation, resembling this:

MapSet.new([:apple, :banana])
#MapSet<[:apple, :banana]>

This is generally done when the struct content or part of it is private and the
%name{...} representation would reveal fields that are not part of the public
API.

The downside of the #name<...> convention is that the inspected output is not
valid Elixir code. For example, you cannot copy the inspected output and paste
it into an IEx session.

Elixir v1.14 changes the convention for some of the standard-library structs.
The Inspect implementation for those structs now returns a string with a valid
Elixir expression that recreates the struct when evaluated. In the MapSet
example above, this is what we have now:

fruits = MapSet.new([:apple, :banana])
MapSet.put(fruits, :pear)
#=> MapSet.new([:apple, :banana, :pear])

The MapSet.new/1 expression evaluates to exactly the struct that we're
inspecting. This allows us to hide the internals of MapSet, while keeping
it as valid Elixir code. This expression-based inspection has been
implemented for Version.Requirement, MapSet, and Date.Range.

Finally, we have improved the Inspect protocol for structs so that
fields are inspected in the order they are declared in defstruct.
The option :optional has also been added when deriving the Inspect
protocol, giving developers more control over the struct representation.
See the updated documentation for Inspect for a general rundown on
the approaches and options available.

1. Enhancements

EEx

• [EEx] Support multi-line comments to EEx via <%!-- --%>
• [EEx] Add EEx.tokenize/2

Elixir

• [Access] Add Access.slice/1
• [Application] Add Application.compile_env/4 and Application.compile_env!/3 to read the compile-time environment inside macros
• [Calendar] Support ISO8601 basic format parsing with DateTime.from_iso8601/2
• [Calendar] Add day/hour/minute on add/diff across different calendar modules
• [Code] Add :normalize_bitstring_modifiers to Code.format_string!/2
• [Code] Emit deprecation and type warnings for invalid options in on Code.compile_string/2 and Code.compile_quoted/2
• [Code] Warn if an outdated lexical tracker is given on eval
• [Code] Add Code.env_for_eval/1 and Code.eval_quoted_with_env/3
• [Code] Improve stacktraces from eval operations on Erlang/OTP 25+
• [Code.Fragment] Add support for __MODULE__ in several functions
• [Code.Fragment] Support surround and context suggestions across multiple lines
• [Enum] Allow slicing with steps in Enum.slice/2
• [File] Support dereference_symlinks: true in File.cp/3 and File.cp_r/3
• [Float] Do not show floats in scientific notation if below 1.0e16 and the fractional value is precisely zero
• [Float] Add Float.min_finite/0 and Float.max_finite/0
• [Inspect] Improve error reporting when there is a faulty implementation of the Inspect protocol
• [Inspect] Allow :optional when deriving the Inspect protocol for hiding fields that match their default value
• [Inspect] Inspect struct fields in the order they are declared in defstruct
• [Inspect] Use expression-based inspection for Date.Range, MapSet, and Version.Requirement
• [IO] Support Macro.Env and keywords as stacktrace defini...

v1.14.0-rc.1

Release v1.14.0-rc.1

v1.14.0-rc.0

Release v1.14.0-rc.0

v1.13.4

This release has been verified to work with Erlang/OTP 25 RC2.

1. Enhancements

Elixir

• [Code] Allow iodata to be returned in sigil formatting functions
• [Code] Pass opening delimiter information to sigil formatting functions

2. Bug fixes

Elixir

• [Kernel] Tweak type unification to fix infinite loop with recursive vars
• [Kernel] Add compile-time dependencies on require
• [Registry] Make Registry send work with named triplets

3. Deprecations

Mix

• [mix rebar] Deprecate Rebar 2 as it no longer works on Erlang/OTP 25

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