v1.2.0

Official announcement: https://elixir-lang.org/blog/2016/01/03/elixir-v1-2-0-released/

1. Enhancements

Elixir

• [Application] Add spec/1 and spec/2 to retrieve application specification
• [Application] Add get_application/1 to retrieve the application a given module belongs to
• [Base] Optimize encode and decode operations about 10 times
• [Enum] Use the faster and auto-seeding :rand instead of :random in Enum.shuffle/1 and Enum.random/1 and Enum.take_random/2
• [Enum] Add Enum.with_index/2
• [GenServer] Add GenServer.stop/1 for shutting down servers reliably
• [IO] Add color related functions to IO.ANSI
• [Kernel] Support multiple aliases in alias, import, require and use. For example, alias MyApp.{Foo, Bar, Baz}
• [Kernel] Add struct!/2. Similar to struct/2 but raises on invalid keys
• [Kernel] Warn if @doc/@typedoc/@moduledoc attributes are redefined
• [Kernel] Warn if non-variables are used in defdelegate/2 (as they have no effect)
• [Kernel] Mark quoted expressions as generated, avoiding false positives on dialyzer
• [Kernel] Allow variables as map keys on creation %{key => value} and on matches %{^key => value}
• [Kernel] Allow the pin operator ^ in fn clauses and on the left side of <- in for comprehensions
• [Kernel] Introduce with as a special form that allows matching on right side parameters
• [Kernel] Warn when right hand side of -> does not provide any expression
• [Kernel] Warn if the Elixir was compiled with a different endianness than the one currently available at runtime
• [Kernel] Warn if a variable is used after being defined exclusively in a nested context
• [Kernel] Warn if piping into an expression without parentheses
• [Macro] Add Macro.traverse/4 that performs pre and post-walk at once
• [Macro] Add Macro.camelize/1 and Macro.underscore/1
• [Process] Add Process.get_keys/0
• [Stream] Add Stream.with_index/2
• [String] Introduce String.replace_{prefix,suffix,leading,trailing}/2. The first two will replace only the first occurrence of the given match in string. The last two will replace all occurrences of the given match
• [String] Support String.normalize/2 and String.equivalent?/2 that perform NFD and NFC normalization
• [System] Add System.time_offset, System.monotonic_time, System.system_time, System.convert_time_unit and System.unique_integer
• [System] Allow System.cmd/3 to remove variables by specifying nil values
• [Task] Add Task.Supervisor.async_nolink/1/3 that spawns a supervised task without linking to the caller process
• [Task] Introduce Task.yield_many/2
• [Task] Raise an error when a task is queried from a non-owning process (instead of waiting forever)

ExUnit

• [ExUnit] Allow one test to raise multiple errors. The goal is to enable tools in the ecosystem to emit multiple failure reports from the same test
• [ExUnit] Support @tag report: [:foo, :bar] which will include the values for tags :foo and :bar whenever a test fails

IEx

• [IEx] Allow IEX_WITH_WERL to be set on Windows to always run on WERL mode
• [IEx] Display type docs for t(Module.type) and t(Module.type/arity)
• [IEx] Add i/1 helper that prints information about any data type
• [IEx] Show source code snippet whenever there is a request to pry a given process

Logger

• [Logger] Add file to logger metadata

Mix

• [Mix] Cache and always consolidate protocols
• [Mix] Add warn_test_pattern to mix test that will warn on potentially misconfigured test files
• [Mix] Introduce MIX_QUIET environment variable that configures the underlying Mix task to output only error messages
• [Mix] Introduce MIX_DEBUG environment variable that prints information about the task being run
• [Mix] Validate git options and warn on conflicting ref, branch or tags
• [Mix] New umbrella applications will now share configuration and build files
• [Mix] Add experimental support for Rebar 3
• [Mix] Do not warn when an optional dependency has a conflicting :only option with another dependency
• [Mix] Raise readable error message when parsertools is not available
• [Mix] Add --build flag to mix deps.clean DEP to only remove artifacts from _build

2. Bug fixes

Kernel

• [Access] Improve error messages when using Access on non-valid key-value structures
• [Kernel] Raise when conflicting :only and :except are given to import
• [Kernel] Change __ENV__.file if @file is set for the given function
• [Kernel] Make Kernel.ParallelRequire aware of :warning_as_errors
• [Kernel] Improve error message for invalid do/do:
• [Macro] Ensure Macro.to_string/2 respects operator precedence when using the access operator
• [Path] Do not crash when expanding paths that go beyond the root, for example, Path.expand("/../..")
• [String] Ensure UnicodeConversionError does not contain invalid string in its error message

IEx

• [IEx] Do not start apps on recompile helper if --no-start was given
• [IEx] Avoid copying of data when evaluating every expression in IEx

Mix

• [Mix] Always run non-recursive tasks at the umbrella root
• [Mix] Ensure rebar projects work on directory names that contain non-latin characters
• [Mix] Ignore directories inside apps in umbrellas that do not have a mix.exs file
• [Mix] Ensure Mix can be used with path dependencies where the app name is different than the path basename
• [Mix] Ensure dependencies won't crash when updating from a git repository to a hex repository and the git version did not respect SemVer
• [Mix] Do not run remote converger if dependencies have diverged
• [Mix] Ensure umbrella dependencies across all environments are loaded on parent deps.get/deps.update

ExUnit

• [ExUnit] Include file and line in all compilation errors for doctests

3. Soft deprecations (no warnings emitted)

Kernel

• [Dict] Dict and HashDict are soft deprecated in favor of Map
• [Keyword] Keyword.size/1 is deprecated in favor of length/1
• [Map] Map.size/1 is deprecated in favor of map_size/1
• [Set] Set and HashSet are soft deprecated in favor of MapSet

Mix

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