Changelog for Elixir v1.4

April 28, 2018 · View on GitHub

Elixir v1.4 brings new features, enhancements and bug fixes into Elixir. The most notable changes are the addition of the Registry module and the Task.async_stream/3 and Task.async_stream/5 which aid developers in writing concurrent software. Those two features and a couple other improvements are described in detail below followed by the complete list of changes.

Registry

The registry is a local, decentralized and scalable key-value process storage:

Local because keys and values are only accessible to the current node (opposite to distributed)
Decentralized because there is no single entity responsible for managing the registry
Scalable because performance scales linearly with the addition of more cores upon partitioning

A registry is chosen upon start to have unique or duplicate keys. Every key-value pair is associated to the process registering the key. Keys are automatically removed once the owner process terminates.

iex> Registry.start_link(:unique, MyRegistry)
iex> {:ok, _} = Registry.register(MyRegistry, "hello", 1)
iex> Registry.lookup(MyRegistry, "hello")
[{self(), 1}]

With the registry, developers can provide dynamic process names, module-function dispatch or even a local pubsub system. See the Registry documentation for more information.

Syntax coloring

Elixir v1.4 introduces the ability to syntax color inspected data structures:

iex> IO.puts inspect([hello: 1, world: "!"], syntax_colors: [atom: :cyan])
[hello: 1, world: "!"]

Coloring is done with ANSI colors as specified in the IO.ANSI module.

IEx automatically relies on this feature to provide syntax coloring for evaluated shell results. This behaviour can be configured via the :syntax_colors coloring option:

IEx.configure [colors: [syntax_colors: [atom: :cyan, string: :green]]]

To disable coloring altogether, pass an empty list to :syntax_colors.

Calendar

Elixir v1.3 introduced new calendar types. This release continues evolving the Calendar APIs by adding functions for comparing, adding and calculating the difference between types, retrieve the day_of_week/1, check if the current date is a leap_year?/1 and more.

Task.async_stream

When there is a need to traverse a collection of items concurrently, Elixir developers often resort to tasks:

collection
|> Enum.map(&Task.async(SomeMod, :function, [&1]))
|> Enum.map(&Task.await/1)

While the snippet above works fine in many occasions, for large collections it will spawn and run concurrently as many tasks as there are items in the collection.

Task.async_stream/3 and Task.async_stream/5 allows developers to process collections concurrently while controlling the maximum amount of concurrent tasks:

collection
|> Task.async_stream(SomeMod, :function, [], max_concurrency: System.schedulers_online)

The Task.async_stream functions are also lazy, allowing developers to partially consume the stream until a condition is reached. Furthermore, Task.Supervisor.async_stream/4 and Task.Supervisor.async_stream/6 can be used to ensure the concurrent tasks are spawned under a given supervisor.

Application inference

Mix v1.4 now automatically infers the list of applications that are required on runtime from your dependencies list.

In previous Mix versions, most of your dependencies had to be added both to your dependencies list and applications list. Here is how a mix.exs would look like:

def application do
  [applications: [:logger, :plug, :postgrex]]
end

def deps do
  [{:plug, "~> 1.2"},
   {:postgrex, "~> 1.0"}]
end

This was error prone as many developers would not list their dependencies in their applications list.

Mix v1.4 now automatically infers your applications list as long as you leave the :applications key empty. The mix.exs above can be rewritten to:

def application do
  [extra_applications: [:logger]]
end

def deps do
  [{:plug, "~> 1.2"},
   {:postgrex, "~> 1.0"}]
end

With the above, Mix will automatically build your application list based on your dependencies. Applications that are part of Erlang or Elixir that are required at runtime, such as :logger, must be added to the :extra_applications list. All extra applications will be included in the application list.

Finally, if there is a dependency you don't want to include in the application runtime list, you can do so by specifying the runtime: false option:

{:distillery, "> 0.0.0", runtime: false}

We hope this feature provides a more streamlined workflow for developers who are building releases for their Elixir projects.

Mix install from SCM

Mix v1.4 can now install escripts and archives from both Git and Hex, providing you with even more options for distributing Elixir code.

This makes it possible to distribute CLI applications written in Elixir by publishing a package which builds an escript to Hex. ex_doc has been updated to serve as an example of how to use this new functionality.

Simply running:

mix escript.install hex ex_doc

will fetch ex_doc and its dependencies, build them, and then install ex_doc to ~/.mix/escripts (by default). After adding ~/.mix/escripts to your PATH, running ex_doc is as simple as:

ex_doc

You can now also install archives from Hex in this way. Since they are fetched and built on the user's machine, they do not have the same limitations as pre-built archives. However, keep in mind archives run alongside every Mix project, which may lead to conflicts. For this reason, escripts is the preferred format.

It is also possible to install escripts and archives by providing a Git/GitHub repo. See mix help escript.install and mix help archive.install for more details.

[Logger] Handle changes to crash reports in OTP 20

2. Bug fixes

Elixir

[DateTime] Fix DateTime.from_iso8601/2 when offset has no colon
[Registry] Do not leak EXIT messages on Registry.dispatch/3

[Map] Fix regression on struct update syntax

[Kernel] Improve compilation time for modules with many clauses
[Map] Warn when attempting to override __struct__ key
[Regex] Add recompile/1 and recompile!/1 to ease transition to OTP 20 for archives and stored regexes

Logger

[Logger.Translator] Handle OTP 20 GenServer log messages

Mix

[mix compile] Recompile projects if OTP version changes

2. Bug fixes

Elixir

[Kernel] Fix code generation when non-binary bitstrings are in AST
[Record] Properly escape fields passed to defrecord
[Version] Reject leading zeros according to the SemVer spec

ExUnit

[ExUnit.Diff] Do not fail when comparing maps with nil or boolean keys

IEx

[IEx.Helpers] Do not log exits on IEx.Helpers.c/2 failures

Mix

[mix archive.install] Detect proper path on URLs with query strings
[mix loadpaths] Do not assume all paths in loadpaths exist

[EEx] Support middle expressions on trim mode

Elixir

[Calendar] Correct typo on Calendar types
[Kernel] Ensure redefined functions point to the proper source
[OptionParser] Add :allow_nonexistent_atoms to support unsafe behaviour prior to v1.4
[Stream] Allow consuming multiple items from suspended enumerable in Stream.transform/3
[String] Incorporate new grapheme rules in Unicode 9

IEx

[IEx.Autocomplete] Do not crash on aliases which are not known at compile time

Mix

[Mix.Umbrella] Ensure umbrella projects can depend on other umbrella projects
[Mix.Archive] Ensure previous archives with .ez extension are deleted

[Kernel] Remove warning when making private functions overridable
[Path] Ensure Path.join/1 returns strings for lists of one element
[Regex] Ensure Regex.escape/1 also escapes -

IEx

[IEx] Disable ANSI detection for powershell to avoid false positives

Mix

[Mix.Make] Run make clean for erlang.mk
[Mix.Rebar] Support all of rebar3 dependency package declaration
[Mix.Rebar] Only pass overrides from parent to child in Rebar dep

[Calendar] Add Date.compare/2, Time.compare/2, NaiveDateTime.compare/2 and DateTime.compare/2
[Calendar] Support NaiveDateTime.add/3 and NaiveDateTime.diff/3 for adding seconds (up to microseconds) as well as the difference between two NaiveDateTimes in seconds (up to microseconds)
[Calendar] Add Date.leap_year?/1 and Date.day_of_week/1
[Calendar] Ensure Date, Time and NaiveDateTime APIs work with any struct that provides the same set of fields as their respective struct. For example, a NaiveDateTime can be given to Date since it contains a superset of the fields in the Date struct
[Calendar] Add Time.utc_now/0 and NaiveDateTime.utc_now/0
[Enum] Add Enum.map_every/2 that invokes the given function with every nth item
[Enum] Add min/2, max/2, min_max/2, min_by/3, max_by/3, and min_max_by/3 that allow a function specifying the default value when the enumerable is empty
[Enum] Introduce Enum.zip/1 to zip multiple entries at once
[Float] Introduce Float.ratio/1 that returns a tuple with the numerator and denominator as integers to retrieve the given float
[GenServer] Log warn on default handle_info/2 implementation
[Inspect] Support syntax coloring via the :syntax_color option
[Integer] Integer.digits/2 now accepts negative integers
[Integer] Add Integer.mod/2 and Integer.floor_div/2
[IO] Add :label option to IO.inspect/2 to help distinguish multiple IO.inspect/2 calls.
[Kernel] Recognize merge conflict markers in source and provide a readable error message
[Kernel] Warn on unused module attributes
[Kernel] Improve compiler message on unexpected end of line
[Kernel] Raise BadBooleanError when a non-boolean is given on the left-hand side of and/or
[List] Add List.pop_at/3
[List] Add List.myers_difference/2
[OptionParser] Expand multi-letter aliases in OptionParser
[Process] Add Process.send_after/4
[Process] Improve error messages on Process.register/2 errors
[Registry] Add a local, decentralized and scalable key-value process storage
[Stream] Add Stream.map_every/2 that invokes the given function with every nth item
[Stream] Introduce Stream.zip/1 to lazily zip multiple entries at once
[String] Update to Unicode 9.0.0
[Task] Add Task.async_stream/3 and Task.async_stream/5 as well as the supervised versions Task.Supervisor.async_stream/4 and Task.Supervisor.async_stream/6
[URI] Allow 0 as URI scheme default port

ExUnit

[ExUnit.Diff] Use red or green background for whitespace-only diffs
[ExUnit.Doctest] Allow inspected structures with multiples lines and unicode characters in the doctest result
[ExUnit.Formatter] Replace lhs/rhs with left/right in the formatter for clarity

IEx

[IEx.Autocomplete] Stop appending a trailing dot when autocompleting modules in IEx
[IEx.Autocomplete] Support autocompletion for structs
[IEx.Autocomplete] Improve IEx autocomplete to support navigating map atom keys
[IEx.Helpers] c/1 now compiles in memory by default to avoid common issue where .beam files remain at projects root directory
[IEx.Helpers] Add info about protocols in i/1
[IEx.Server] Support interrupting IEx evaluation through the Ctrl+G prompt

Mix

[mix archive] Compress archive files built by mix archive as they are now unzipped during installation
[mix archive] Install from SCM
[mix compile] Automatically infer the list of applications for Mix projects
[mix cmd] Add the ability to specify one or more apps in mix cmd
[mix deps] Warn if there are non-applications in the apps directory for umbrella projects
[mix deps] Add warning for invalid paths on mix deps.clean
[mix deps] Add Mix.Project.apps_paths that returns the paths to children applications in umbrella projects
[mix deps] Add MIX_REBAR environment variable for overriding local rebar
[mix escript] Install from SCM
[mix new] Check directory existence in mix new and ask how to proceed if one exists
[mix new] Applications built with the --sup flag now have an individual module to work as application callback
[mix test] Add --formatter option to mix test
[mix xref] Provide "did you mean?" suggestions for mix xref

2. Bug fixes

Elixir

[Access] Do not accept nils in Access.key/1 and Access.key/2 in favor of explicit default values (or Access.key!/1 if you expect the key to always be available)
[Float] Avoid multiple roundings in Float.ceil/2, Float.floor/2 and Float.round/2
[Kernel] Don't crash in macro_exported?/3 when dealing with Erlang modules
[Kernel] Ensure locals calls are rewritten when calling a local function or macro from inside a module
[Kernel] Annotate the context for variables as zero-arity funs in quotes
[Kernel.SpecialForms] Ensure comprehensions with guards and filters keep proper ordering,
[Kernel.SpecialForms] Produce meaningful warning when with's else clauses have no effect
[Macro] Wrap fn calls in parens in Macro.to_string/2
[Macro] Do not print aliases as keys inside keyword lists in Macro.to_string/2
[OptionParser] Support options in OptionParser.to_argv/2 to ensure :count switches are correctly encoded
[Stream] Ensure Stream.take/2 does not consume next element on :suspend
[String] Fix infinite recursion in String.replace_leading/3 and String.replace_trailing/3 when given an empty string
[Task] Fix Task.shutdown/1,2 infinite block when task has no monitor
[Task] Ensure task cannot link after parents unlinks

ExUnit

[ExUnit] Fix a race condition in assert_receive where we would assert a message was not received but show it in the list of messages when the message is delivered right after the timeout value

IEx

[IEx.Helpers] Purge consolidated protocols before and after recompile/0

Mix

[Mix.Dep] Use gmake on FreeBSD instead of make when compiling make dependencies
[Mix.Project] Only copy files from source when they're newer than destination (for Windows machines)
[Mix.Task] Ensure non-recursive tasks inside umbrella are reenabled

3. Soft deprecations (no warnings emitted)

Elixir

[Enum] Enum.partition/2 has been deprecated in favor of Enum.split_with/2
[System] Deprecate plural time units in favor of singular ones to align with future Erlang releases

ExUnit

[ExUnit] Using GenEvent to implement ExUnit formatters is deprecated. Please use the new GenServer based formatters instead

4. Deprecations

Elixir

[Access] Access.key/1 is deprecated due to erratic behaviour for missing keys, please use Access.key/2 instead with proper default values
[Behaviour] The Behaviour module is deprecated. Callbacks may now be defined directly via the @callback attribute
[Enum] Deprecate Enum.uniq/2 in favor of Enum.uniq_by/2
[Float] Float.to_char_list/2 and Float.to_string/2 are deprecated (use the :erlang.float_to_list/2 and :erlang.float_to_binary/2 functions if such conversions are desired) * [HashDict] The HashDict module is deprecated, in favour of the Map * [HashSet] The HashDict module is deprecated, in favour of the MapSet
* [Kernel] Deprecate support for making private functions overridable. Overridable functions must always be public as they must be contracts
[Kernel] Anonymous functions with no expression after ->, in favor of using an expression or returning nil
[Kernel] Warn if variable is used as a function call
[OptionParser] Deprecate aliases with multiple letters, such as -abc
[Set] Deprecation of the Set module in favor of MapSet
[Stream] Deprecate Stream.uniq/2 in favor of Stream.uniq_by/2

IEx

[IEx.Helpers] import_file/2 is deprecated in favor of import_file_if_available/1

Mix

[Mix.Utils] underscore/1 and camelize/1 are deprecated in favor of Macro.underscore/1 and Macro.camelize/1

v1.3

The CHANGELOG for v1.3 releases can be found in the v1.3 branch.