Erlang/OTP 29.0 – Erlang/OTP

OTP 29.0 #

Erlang/OTP 29 is a new major release with new features, improvements
as well as a few incompatibilities. Some of the new features are
highlighted below.

Many thanks to all contributors!

• Added support for -unsafe attributes for marking
  functions as unsafe to use. The compiler will by default now
  generate warnings for calls to functions in Erlang/OTP known to be
  always unsafe. Furthermore, xref can now be used to find calls to
  unsafe functions and functions that lack documentation.

• The SSH daemon now defaults to disabled for shell and exec services,
  implementing the “secure by default” principle. This prevents
  authenticated users from executing arbitrary Erlang code unless
  explicitly configured.

• The SFTP subsystem is no longer enabled by default when starting an
  SSH daemon.

• In SSL, the post quantum hybrid algorithm x25519mlkem768 is now the
  most preferred key exchange group in the default configuration.

• The module io_ansi allows the user to emit Virtual Terminal
  Sequences (also known as ANSI sequences) to the terminal in order to
  add colors/styling to text or to create fully fledged terminal
  applications.

• The new ct_doctest module allows the user to test
  documentation examples in Erlang module docs and documentation files.

• The ignore_xref attribute has been handled as a post-analysis
  filter by build tools such as Rebar3. In this release, [xref]
  itself does the filtering, ensuring that all tooling that calls
  xref for any purpose can rely on these declarations to just work.

General #

• In the default code path for the Erlang system, the current working
  directory (.) is now in the last position instead of the first.

• There is no longer a 32-bit Erlang/OTP build for Windows.

New language features #

• Native records as described in
  EEP-79 has been
  implemented. A native record is a data structure similar to the
  traditional tuple-based records, except that is a true data type.
  Native records are considered experimental in Erlang/OTP 29 and
  possibly also in Erlang/OTP 30.

• The new is_integer/3 guard BIF makes it possible to easily verify
  that a value is both an integer and within a certain range. For
  example: is_integer(I, 0, 100)

• Multi-valued comprehensions according to EEP 78
  are now supported. For example, [-I, I || I <- [1, 2, 3]] will produce
  [-1,1,-2,2,-3,3].

• By enabling the compr_assign feature, it is now possible to bind variables
  in a comprehensions. For example:
  [H || E <- List, H = erlang:phash2(E), H rem 10 =:= 0]

Compiler and JIT improvements #

• In the documentation for the [compile] module, there is now a section
  with recommendations for implementors of languages running on
  the BEAM.

• The JIT now generates better code for matching or creating binaries with
  multiple little-endian segments.

• The compiler will generate more efficient code for map
  comprehensions with constant values that don’t depend on the
  generator. Example: #K => 42

Compiler warnings #

There are several new compiler warnings enabled by default. For each
such warning, there is an option to disable it.

• There will now be a warning when using the catch operator, which
  has been deprecated for a long time. It is recommended to instead
  use try…catch but is also possible to disable the warning
  by using the nowarn_deprecated_catch option.

• There will now be a warning when exporting variables out of a
  subexpression. For example: file:open(File, AllOpts = [write,
⚡]). This warning can be disabled using the
  nowarn_export_var_subexpr compiler option.

• The compiler will now warn for uses of the and and or
  operators. This warning can be disabled using the
  nowarn_obsolete_bool_op compiler option.

• The compiler will now warn for matches such as ⚡ = 💬,
  which is better written as 💬. This warning can be disabled
  using the nowarn_match_alias_pats option.

For a long time, there has been a warning for using the obsolete guard
tests (such as list(L) instead of is_list(L). In Erlang/OTP 30, the
old guards will be removed from the language.

STDLIB #

• There are new functions for randomly permutating a list: rand:shuffle/1 and
  rand:shuffle_s/2.

SSH #

• The default key exchange algorithm is now mlkem768x25519-sha256, a hybrid
  quantum-resistant algorithm combining ML-KEM-768 with X25519. This provides
  protection against both classical and quantum computer attacks while
  maintaining backward compatibility through automatic fallback to other
  algorithms when peers don’t support it.

For a full list and more details about new features and potential incompatibilities see the README.