v1.18.2

1. Enhancements

Elixir

• [CLI] Add --color/--no-color for enabling and disabling of ANSI colors
• [Code.Fragment] Provide more AST context when invoking container_cursor_to_quoted with trailing fragments
• [Regex] Ensure compatibility with Erlang/OTP 28+ new Regex engine

Mix

• [mix] Print compilation lock waiting message to stderr
• [mix] Add an environment variable to optionally disable compilation locking

2. Bug fixes

Elixir

• [CLI] Temporarily remove PowerShell scripts for elixir, elixirc, and mix on Windows, as they leave the shell broken after quitting Erlang

ExUnit

• [ExUnit] Fix crash when diffing bitstring specifiers

IEx

• [IEx.Autocomplete] Fix crashing whhen autocompleting structs with runtime values

Mix

• [mix] Track compilation locks per user to avoid permission errors
• [mix deps.update] Ensure Git dependencies can be upgraded by doing so against the origin

v1.18.1

1. Enhancements

• [Kernel] Do not emit type violation warnings when comparing or matching against literals
• [Kernel] Do not validate clauses of private overridable functions

2. Bug fixes

Elixir

• [Code.Fragment] Ensure Code.Fragment.container_cursor_to_quoted/2 with :trailing_fragment parses expressions that were supported in previous versions
• [Kernel] Do not crash when typing violation is detected on dynamic dispatch
• [Kernel] Properly annotate the source for warnings emitted by the compiler with the @file annotation
• [Kernel] Properly annotate the source for warnings emitted by the type system with the @file annotation
• [Kernel] Remove :no_parens metadata when using capture with arity on all cases
• [Kernel] Ensure diagnostic traces are kept backwards compatible

ExUnit

• [ExUnit.Case] Ensure async groups do not run concurrenly while the test suite is still loading
• [ExUnit.Case] Ensure --repeat-until-failure can be combined with groups

Mix

• [mix compile.elixir] Store compilation results if compilation fails due to --warnings-as-errors
• [mix deps.loadpaths] Add build lock
• [mix escript.build] Ensure build succeeds when protocol consolidation is disabled
• [Mix.Shell] Ensure encoding is properly respected on Windows and Unix systems

v1.18.0

Official announcement: https://elixir-lang.org/blog/2024/12/19/elixir-v1-18-0-released/

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
• [Calendar] Add Duration.to_string/1
• [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] Include more metadata in Code.string_to_quoted/2 when token_metadata: true to help compute ranges from the AST
• [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
• [JSON] Add a new JSON module with encoding and decoding functionality
• [JSON] Implement JSON.Encoder for all Calendar types
• [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] Verify the type of the binary generators
• [Kernel] Track the type of tuples in patterns and inside elem/2
• [Kernel] Perform validation of root AST nodes in unquote and unquote_splicing to catch bugs earlier
• [Kernel] Add source, behaviour, and record information to Docs chunk metadata
• [Kernel] Support deterministic builds in tandem with Erlang by setting ERL_COMPILER_OPTIONS=deterministic. Keep in mind deterministic builds strip source and other compile time information, which may be relevant for programs
• [Kernel] Allow aliases and imports to be enabled conditionally in module body
• [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)
• [Registry] Add Registry.lock/3 for local locking
• [PartitionSupervisor] Add PartitionSupervisor.resize!/2 to resize the number of partitions in a supervisor (up to the limit it was started with)
• [Process] Handle arbitrarily high integer values in Process.sleep/1
• [Protocol] Add @undefined_impl_description to customize error message when an implementation is undefined
• [Protocol] Add __deriving__/1 as optional macro callback to Protocol, no longer requiring empty implementations
• [String] Inspect special whitespace and zero-width characters using their Unicode representation
• [String] Update Unicode to 16.0

ExUnit

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

IEx

• [IEx] Add IEx.configure(auto_reload: true) to automatically pick up modules recompiled from other operating system processes
• [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 format] Add new options and metadata to improve formatting applying by editors and other environments
• [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] Fix delimiter metadata for single quoted atoms and remote calls in Code.string_to_quoted/2
• [Code.Formatter] Fix formatter adding extra escapes to quoted remote calls
• [Code.Fragment] Properly handle keyword keys as their own entry
• [Inspect.Algebra] Ensure next_break_fits respects line_length
• [Kernel] Validate AST on unquote and unquote_splicing to provide better error reports instead of failing too late inside the compiler
• [Kernel] Avoid crashes when emitting diagnostics on code using \t for indentation
• [Module] Include module attribute line and name when tracing its aliases
• [Stream] Do not halt streams twice in Stream.transform/5
• [URI] Fix a bug when a schemaless URI is given to URI.merge/2

ExUnit

• [ExUnit.Assertions] Raise if guards are used in assert/1 with =
• [ExUnit.Assertions] Format inserted/deleted maps in list assertions

IEx

• [IEx.Helpers] IEx.Helpers.recompile/0 will reload modules changed by other operating system processes

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
• [Mix.Shell] Fix Mix.Shell on Windows when outputting non UTF-8 characters

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
• [Protocol] Defining __deriving__/3 inside the Any implementation is deprecated, derive it inside the protocol definition itself

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

• [Code] Setting :warnings_as_errors is deprecated via Code.put_compiler_option/2. This must not affect developers, as the :warnings_as_errors option is managed by Mix tasks, and not directly used via the Code module
• [Enumerable] Deprecate returning a two-arity function in Enumerable.slice/1
• [List] List.zip/1 is deprecated in favor of Enum.zip/1
• [Module] Deprecate Module.eval_quoted/3 in favor of Code.eval_quoted/3
• [Range] Deprecate inferring negative ranges on Range.new/2
• [Tuple] Tuple.append/2 is deprecated, use Tuple.insert_at/3 instead

Mix

• [mix cmd] Deprecate mix cmd --app APP in favor of mix do --app APP
• [mix compile] :warnings_as_errors configuration in :elixirc_options is deprecated. Instead pass the --warnings-as-errors flag to mix compile. Alternatively, you might alias the task: aliases: [compile: "compile --warnings-as-errors"]
• [mix test] :warnings_as_errors configuration in :test_elixirc_options is deprecated. Instead pass the --warnings-as-errors flag to mix test. Alternatively, you might alias the task: aliases: [test: "test --warnings-as-errors"]
• [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.

v1.18.0-rc.0

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
• [Calendar] Add Duration.to_string/1
• [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] Include more metadata in Code.string_to_quoted/2 when token_metadata: true to help compute ranges from the AST
• [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] Verify the type of the binary generators
• [Kernel] Track the type of tuples in patterns and inside elem/2
• [Kernel] Perform validation of root AST nodes in unquote and unquote_splicing to catch bugs earlier
• [Kernel] Add source, behaviour, and record information to Docs chunk metadata
• [Kernel] Support deterministic builds in tandem with Erlang by setting ERL_COMPILER_OPTIONS=deterministic. Keep in mind deterministic builds strip source and other compile time information, which may be relevant for programs
• [Kernel] Allow aliases and imports to be enabled conditionally in module body
• [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)
• [Registry] Add Registry.lock/3 for local locking
• [PartitionSupervisor] Add PartitionSupervisor.resize!/2 to resize the number of partitions in a supervisor (up to the limit it was started with)
• [Process] Handle arbitrarily high integer values in Process.sleep/1
• [Protocol] Add @undefined_impl_description to customize error message when an implementation is undefined
• [Protocol] Add __deriving__/1 as optional macro callback to Protocol, no longer requiring empty implementations
• [String] Inspect special whitespace and zero-width characters using their Unicode representation
• [String] Update Unicode to 16.0

ExUnit

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

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 format] Add new options and metadata to improve formatting applying by editors and other environments
• [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] Fix delimiter metadata for single quoted atoms and remote calls in Code.string_to_quoted/2
• [Code.Formatter] Fix formatter adding extra escapes to quoted remote calls
• [Code.Fragment] Properly handle keyword keys as their own entry
• [Inspect.Algebra] Ensure next_break_fits respects line_length
• [Kernel] Validate AST on unquote and unquote_splicing to provide better error reports instead of failing too late inside the compiler
• [Module] Include module attribute line and name when tracing its aliases
• [Stream] Do not halt streams twice in Stream.transform/5
• [URI] Fix a bug when a schemaless URI is given to URI.merge/2

ExUnit

• [ExUnit.Assertions] Raise if guards are used in assert/1 with =
• [ExUnit.Assertions] Format inserted/deleted maps in list assertions

IEx

• [IEx.Helpers] IEx.Helpers.recompile/0 will reload modules changed by other operating system processes

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
• [Mix.Shell] Fix Mix.Shell on Windows when outputting non UTF-8 characters

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
• [Protocol] Defining __deriving__/3 inside the Any implementation is deprecated, derive it inside the protocol definition itself

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

• [Code] Setting :warnings_as_errors is deprecated via Code.put_compiler_option/2. This must not affect developers, as the :warnings_as_errors option is managed by Mix tasks, and not directly used via the Code module
• [Enumerable] Deprecate returning a two-arity function in Enumerable.slice/1
• [List] List.zip/1 is deprecated in favor of Enum.zip/1
• [Module] Deprecate Module.eval_quoted/3 in favor of Code.eval_quoted/3
• [Range] Deprecate inferring negative ranges on Range.new/2
• [Tuple] Tuple.append/2 is deprecated, use Tuple.insert_at/3 instead

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

v1.17.3

1. Bug fixes

Elixir

• [Duration] Fix parsing of fractional durations with non-positive seconds
• [Kernel] Do not attempt to group module warnings when they have a large context

IEx

• [IEx.Helpers] Properly reconsolidate protocols on recompile

Mix

• [mix compile.elixir] Do not verify modules twice
• [mix xref] Respect the --label option on stats and cycles

v1.17.2

1. Bug fixes

Logger

• [Logger.Translator] Fix logger crash when :gen_statem's format_status/2 returns non-tuple

Mix

• [mix deps.get] Fix regression when fetching a git repository with a :ref
• [mix release] Validate RELEASE_MODE and set ERRORLEVEL on .bat scripts
• [mix release] Fix invalid example in code comment inside the generated vm.args.eex

v1.17.1

1. Enhancements

Mix

• [mix compile.elixir] Do not run fixpoint computation on runtime dependencies. This should considerably improve compilation times for large projects when changing only one or two files

2. Bug fixes

EEx

• [EEx] Do not warn for assignment with blocks in EEx

Elixir

• [Kernel] Fix bug when using pinned variables inside with's else patterns
• [Kernel] Fix Dialyzer error when with else clause is calling a no_return function

ExUnit

• [ExUnit] Do not alternative sync/async suites on --repeat-until-failure

v1.17.0

Official announcement: https://elixir-lang.org/blog/2024/06/12/elixir-v1-17-0-released/

1. Enhancements

Elixir

• [Access] Add Access.find/1 that mirrors Enum.find/2
• [Code] Support cursor inside fn/rescue/catch/else/after inside Code.Fragment.container_cursor_to_quoted/2
• [Date] Add Date.shift/2 to shift dates with duration and calendar-specific semantics
• [Date] Allow Date to accept years outside of -9999..9999 range
• [DateTime] Add DateTime.shift/2 to shift datetimes with duration and calendar-specific semantics
• [Duration] Add a new Duration data type
• [GenServer] Add c:GenServer.format_status/1 callback
• [Kernel] Add Kernel.get_in/1 with safe nil-handling for access and structs
• [Kernel] Add Kernel.is_non_struct_map/1 guard
• [Kernel] Add Kernel.to_timeout/1
• [Kernel] Emit warnings for undefined functions from modules defined within the same context as the caller code
• [Kernel] Support integers in uppercase sigils
• [Keyword] Add Keyword.intersect/2-3 to mirror the Map API
• [Macro] Add Macro.Env.define_alias/4, Macro.Env.define_import/4, Macro.Env.define_require/4, Macro.Env.expand_alias/4, Macro.Env.expand_import/5, and Macro.Env.expand_require/6 to aid the implementation of language servers and embedded languages
• [NaiveDateTime] Add NaiveDateTime.shift/2 to shift naive datetimes with duration and calendar-specific semantics
• [Process] Add Process.set_label/1
• [String] Add String.byte_slice/3 to slice a string to a maximum number of bytes while keeping it UTF-8 encoded
• [System] Support use_stdio: false in System.cmd/3 and System.shell/2
• [Time] Add Time.shift/2 to shift times with duration and calendar-specific semantics

ExUnit

• [ExUnit] Propagate the test process itself as a caller in start_supervised
• [ExUnit] Include max cases in ExUnit reports

IEx

• [IEx.Helpers] Warns if recompile was called and the current working directory changed
• [IEx.Helpers] Add c/0 as an alias to continue/0
• [IEx.Pry] Add IEx.Pry.annotate_quoted/3 to annotate a quoted expression with pry breakpoints

Logger

• [Logger] Format :gen_statem reports using Elixir data structures
• [Logger] Include process label in logger events

Mix

• [mix deps] Add :depth option to Mix.SCM.Git, thus supporting shallow clones of Git dependencies
• [mix deps] Warn if :optional is used in combination with :in_umbrella
• [mix deps.get] Do not add optional dependency requirements if its parent dep was skipped
• [mix deps.tree] Add --umbrella-only to mix deps.tree
• [mix profile.tprof] Add a new profiler, available on Erlang/OTP 27+, which can measure count, time, and heap usage
• [mix test] Add mix test --breakpoints that sets up a breakpoint before each test that will run
• [mix test] Add mix test --repeat-until-failure to rerun tests until a failure occurs
• [mix test] Add mix test --slowest-modules to print slowest modules based on all of the tests they hold
• [mix test] Generate cover HTML files in parallel

2. Bug fixes

Elixir

• [bin/elixir.bat] Improve handling of quotes and exclamation marks in flags
• [Code] Address a bug where AST nodes for (a -> b) were not wrapped as part of the literal encoder
• [Kernel] Resolve inconsistencies of how .. and ... are handled at the AST level
• [Kernel] Fix parsing precedence of ambiguous operators followed by containers
• [Kernel] Do not expand code in quote bind_quoted: ... twice
• [Kernel] Respect :line property when :file is given as option to quote
• [Kernel] Do not crash on Macro.escape/2 when passing a quote triplet without valid meta
• [Kernel] Avoid double tracing events when capturing a function
• [Kernel] Fix a bug where captured arguments would conflict when a capture included a macro that also used captures
• [Module] Return default value in Module.get_attribute/3 for persisted attributes which have not yet been written to

IEx

• [IEx.Helpers] Update the history size whenever history is pruned

Mix

• [mix deps] Fix error message for diverged SCM definition in sibling

3. Soft deprecations (no warnings emitted)

Elixir

• [GenServer] Deprecate c:GenServer.format_status/2 callback to align with Erlang/OTP 25+

Mix

• [mix profile.cprof] Deprecated in favor of the new mix profile.tprof
• [mix profile.eprof] Deprecated in favor of the new mix profile.tprof

4. Hard deprecations

Elixir

• [IO] Passing :all to IO.read/2 and IO.binread/2 is deprecated, pass :eof instead
• [Kernel] Single-quote charlists are deprecated, use ~c instead
• [Kernel] Deprecate escaping closing delimiter in uppercase sigils
• [Range] left..right without explicit steps inside patterns and guards is deprecated, write left..right//step instead
• [Range] Decreasing ranges, such as 10..1 without an explicit step is deprecated, write 10..1//-1 instead

ExUnit

• [ExUnit.Case] register_test/4 is deprecated in favor of register_test/6 for performance reasons

v1.17.0-rc.1

1. Enhancements

Elixir

• [Duration] Add Duration.to_iso8601/1 and Duration.from_iso8601/1
• [Keyword] Add Keyword.intersect/2-3 to mirror the Map API

Mix

• [mix profile.tprof] Add a new profiler, available on Erlang/OTP 27+, which can measure count, time, and heap usage
• [mix test] Generate cover HTML files in parallel

2. Bug fixes

Elixir

• [Kernel] Avoid double tracing events when capturing a function
• [Kernel] Fix a bug where captured arguments would conflict when a capture included a macro that also used captures

3. Soft deprecations

Mix

• [mix profile.cprof] Deprecated in favor of the new mix profile.tprof
• [mix profile.eprof] Deprecated in favor of the new mix profile.tprof

v1.17.0-rc.0

This release includes type inference of patterns to provide warnings for an initial set of constructs (binaries, maps, and atoms). It also includes a new Duration data type to interact with Calendar types and support for Erlang/OTP 27.

Warnings from gradual set-theoretic types

This release introduces gradual set-theoretic types to infer types from patterns and guards and use them to type check programs, enabling the Elixir compiler to find faults and bugs in codebases without requiring changes to existing software. The underlying principles, theory, and roadmap of our work have been outlined in "The Design Principles of the Elixir Type System" by Giuseppe Castagna, Guillaume Duboc, José Valim.

At the moment, Elixir developers will interact with set-theoretic types only through warnings found by the type system. The current implementation models all data types in the language:

• binary(), integer(), float(), pid(), port(), reference() - these types are indivisible. This means both 1 and 13 get the same integer() type.

• atom() - it represents all atoms and it is divisible. For instance, the atom :foo and :hello_world are also valid (distinct) types.

• map() and structs - maps can be "closed" or "open". Closed maps only allow the specified allows keys, such as %{key: atom(), value: integer()}. Open maps support any other keys in addition to the ones listed and their definition starts with ..., such as %{..., key: atom(), value: integer()}. Structs are closed maps with the __struct__ key.

• tuple(), list(), and function() - currently they are modelled as indivisible types. The next Elixir versions will also introduce fine-grained support to them.

We focused on atoms and maps on this initial release as they are respectively the simplest and the most complex types representations, so we can stress the performance of the type system and quality of error messages. Modelling these types will also provide the most immediate benefits to Elixir developers. Assuming there is a variable named user, holding a %User{} struct with an address field, Elixir v1.17 will emit the following warnings at compile-time:

• Pattern matching against a map or a struct that does not have the given key, such as %{adress: ...} = user (notice address vs adress)

• Accessing a key on a map or a struct that does not have the given key, such as user.adress

• Updating a struct or a map that does not define the given key, such as %{user | adress: ...}

• Invoking a function on non-modules, such as user.address()

• Capturing a function on non-modules, such as &user.address/0

• Performing structural comparisons with structs, such as my_date < ~D[2010-04-17]

• Performing structural comparisons between non-overlapping types, such as integer >= string

• Building and pattern matching on binaries without the relevant specifiers, such as <<string>> (this warns because by default it expects an integer)

• Attempting to rescue an undefined exception or an exception that is not a struct

• Accessing a field that is not defined in a rescued exception

These new warnings help Elixir developers find bugs earlier and give more confidence when refactoring code, especially around maps and structs. While some of these warnings were emitted in the past, they were discovered using syntax analysis. The new warnings are more reliable, precise, and with better error messages. Keep in mind that not all maps have statically known keys, and the Elixir typechecker only infers types from patterns at the moment.

Future Elixir versions will infer and type check more constructs, bringing Elixir developers more warnings and quality of life improvements without changes to code. For more details, see our new reference document on gradual set-theoretic types.

The type system was made possible thanks to a partnership between CNRS and Remote. The development work is currently sponsored by Fresha, Starfish*, and Dashbit.

Erlang/OTP support

This release adds support for Erlang/OTP 27 and drops support for Erlang/OTP 24. We recommend Elixir developers to migrate to Erlang/OTP 26 or later, especially on Windows. Support for WERL (a graphical user interface for the Erlang terminal on Windows) will be removed in Elixir v1.18.

Adding Duration and shift/2 functions

Elixir introduces the Duration data type and APIs to shift dates, times, and date times by a given duration, considering different calendars and time zones.

iex> Date.shift(~D[2016-01-31], month: 2)
~D[2016-03-31]

Note the operation is called shift (instead of add) since working with durations does not obey properties such as associativity. For instance, adding one month and then one month does not give the same result as adding two months:

iex> ~D[2016-01-31] |> Date.shift(month: 1) |> Date.shift(month: 1)
~D[2016-03-29]

Still, durations are essential for building intervals, recurring events, and modelling scheduling complexities found in the world around us. For DateTimes, Elixir will correctly deal with time zone changes (such as Daylight Saving Time), but provisions are also available in case you want to surface conflicts (for example, you shifted to a wall clock that does not exist, because the clock has been moved forward by one hour). See DateTime.shift/2 for examples.

Finally, a new Kernel.to_timeout/1 function has been added, which helps developers normalize durations and integers to a timeout used by Process APIs. For example, to send a message after one hour, one can now write:

Process.send_after(pid, :wake_up, to_timeout(hour: 1))

1. Enhancements

Elixir

• [Access] Add Access.find/1 that mirrors Enum.find/2
• [Code] Support cursor inside fn/rescue/catch/else/after inside Code.Fragment.container_cursor_to_quoted/2
• [Date] Add Date.shift/2 to shift dates with duration and calendar-specific semantics
• [Date] Allow Date to accept years outside of -9999..9999 range
• [DateTime] Add DateTime.shift/2 to shift datetimes with duration and calendar-specific semantics
• [Duration] Add a new Duration data type
• [GenServer] Add c:GenServer.format_status/1 callback
• [Kernel] Add Kernel.get_in/1 with safe nil-handling for access and structs
• [Kernel] Add Kernel.is_non_struct_map/1 guard
• [Kernel] Add Kernel.to_timeout/1
• [Kernel] Emit warnings for undefined functions from modules defined within the same context as the caller code
• [Kernel] Support integers in uppercase sigils
• [Macro] Add Macro.Env.define_alias/4, Macro.Env.define_import/4, Macro.Env.define_require/4, Macro.Env.expand_alias/4, Macro.Env.expand_import/5, and Macro.Env.expand_require/6 to aid the implementation of language servers and embedded languages
• [NaiveDateTime] Add NaiveDateTime.shift/2 to shift naive datetimes with duration and calendar-specific semantics
• [Process] Add Process.set_label/1
• [String] Add String.byte_slice/3 to slice a string to a maximum number of bytes while keeping it UTF-8 encoded
• [System] Support use_stdio: false in System.cmd/3 and System.shell/2
• [Time] Add Time.shift/2 to shift times with duration and calendar-specific semantics

ExUnit

• [ExUnit] Propagate the test process itself as a caller in start_supervised
• [ExUnit] Include max cases in ExUnit reports

IEx

• [IEx.Helpers] Warns if recompile was called and the current working directory changed
• [IEx.Helpers] Add c/0 as an alias to continue/0
• [IEx.Pry] Add IEx.Pry.annotate_quoted/3 to annotate a quoted expression with pry breakpoints

Logger

• [Logger] Format :gen_statem reports using Elixir data structures
• [Logger] Include process label in logger events

Mix

• [mix deps] Add :depth option to Mix.SCM.Git, thus supporting shallow clones of Git dependencies
• [mix deps] Warn if :optional is used in combination with :in_umbrella
• [mix deps.get] Do not add optional dependency requirements if its parent dep was skipped
• [mix deps.tree] Add --umbrella-only to mix deps.tree
• [mix test] Add mix test --breakpoints that sets up a breakpoint before each test that will run
• [mix test] Add mix test --repeat-until-failure to rerun tests until a failure occurs
• [mix test] Add mix test --slowest-modules to print slowest modules based on all of the tests they hold

2. Bug fixes

Elixir

• [bin/elixir.bat] Improve handling of quotes and exclamation marks in flags
• [Code] Address a bug where AST nodes for (a -> b) were not wrapped as part of the literal encoder
• [Kernel] Resolve inconsistencies of how .. and ... are handled at the AST level
• [Kernel] Fix parsing precedence of ambiguous operators followed by containers
• [Kernel] Do not expand code in quote bind_quoted: ... twice
• [Kernel] Respect :line property when :file is given as option to quote
• [Kernel] Do not crash on Macro.escape/2 when passing a quote triplet without valid meta
• [Module] Return default value in Module.get_attribute/3 for persisted attributes which have not yet been written to

IEx

• [IEx.Helpers] Update the history size whenever history is pruned

Mix

• [mix deps] Fix error message for diverged SCM definition in sibling

3. Soft deprecations (no warnings emitted)

Elixir

• [GenServer] Deprecate c:GenServer.format_status/2 callback to align with Erlang/OTP 25+

4. Hard deprecations

...