Erlang OTP 28.0 Released

Erlang/BEAM Alerts
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OTP 28.0

Erlang/OTP 28 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!

Starting with this release, a source Software Bill of Materials (SBOM) will describe the release on the Github Releases page.
We welcome feedback on the SBOM.

New language features

  • Functionality making it possible for processes to enable reception of priority messages has been introduced in accordance with EEP 76.

  • Comprehensions have been extended with “zip generators” allowing multiple generators to be run in parallel. For example, [A+B || A <- [1,2,3] && B <- [4,5,6]] will produce [5,7,9].

  • Generators in comprehensions can now be strict, meaning that if the generator pattern does not match, an exception will be raised instead of silently ignore the value that didn’t match.

  • It is now possible to use any base for floating point numbers as per EEP 75: Based Floating Point Literals.

Compiler and JIT improvements

  • For certain types of errors, the compiler can now suggest corrections. For example, when attempting to use variable A that is not defined but A0 is, the compiler could emit the following message: variable 'A' is unbound, did you mean 'A0'?

  • The size of an atom in the Erlang source code was limited to 255 bytes in previous releases, meaning that an atom containing only emojis could contain only 63 emojis. While atoms are still only allowed to contain 255 characters, the number of bytes is no longer limited.

  • The warn_deprecated_catch option enables warnings for use of old-style catch expressions on the form catch Expr instead of the modern try 
 catch 
 end.

  • Provided that the map argument for a maps:put/3 call is known to the compiler to be a map, the compiler will replace such calls with the corresponding update using the map syntax.

  • Some BIFs with side-effects (such as binary_to_atom/1) are optimized in try 
 catch in the same way as guard BIFs in order to gain performance.

  • The compiler’s alias analysis pass is now both faster and less conservative, allowing optimizations of records and binary construction to be applied in more cases.

ERTS

  • The trace:system/3 function has been added. It has a similar interface as erlang:system_monitor/2 but it also supports trace sessions.

  • os:set_signal/2 now supports setting handlers for the SIGWINCH, SIGCONT, and SIGINFO signals.

  • The two new BIFs erlang:processes_iterator/0 and erlang:process_next/1 make it possible to iterate over the process table in a way that scales better than erlang:processes/0.

Shell and terminal

  • The erl -noshell mode has been updated to have two sub modes called raw and cooked, where cooked is the old default behaviour and raw can be used to bypass the line-editing support of the native terminal. Using raw mode it is possible to read keystrokes as they occur without the user having to press Enter. Also, the raw mode does not echo the typed characters to stdout.

  • The shell now prints a help message explaining how to interrupt a running command when stuck executing a command for longer than 5
    seconds.

STDLIB

  • The join(Binaries, Separator) function that joins a list of binaries has been added to the binary module.

  • By default, sets created by module sets will now be represented as maps.

  • Module re has been updated to use the newer PCRE2 library instead of the PCRE library.

  • There is a new zstd module that does Zstandard compression.

Public_key

  • The ancient ASN.1 modules used in public_key has been replaced with more modern versions, but we have strived to keep the documented Erlang API for the public_key application compatible.

Dialyzer

SSL

  • The data handling for tls-v1.3 has been optimized.

Emacs mode (in the Tools application)

  • The indent-region in Emacs command will now handle multiline strings better.

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

Blog post:

EFS Thread:

32 Likes
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Really excited about priority messages, I suspect it will make some of my database-related work easier in the future (e.g. being able to send “control” messages to processes under load). Erlang has made great progress in this area over the years (JIT, splitting up large messages, etc). Many thanks to the core team!

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Interesting feature, however I can see this becoming a mess to debug.

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I can see how it could be abused. There was great consternation about this when the proposal was made, from people with far more experience and knowledge than me.

However in my particular case I have a completely closed system where I can be very deliberate about which messages should be priority, so I think it will be helpful.

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Yet, I have a pet project that will greatly be simplified due to this new feature. Instead having to rely on an external queue with a few handlers to prepend instead of append it can now be controlled ‘on the fly’. Just what it was made for :slight_smile:

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If your project depends on x509 it will currently not work with OTP 28.0, the changes made to the public_key are incompatible and apparentely will take some time to fix, including some changes to OTP.

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I think we’ve all been bitten by the bug of “oops, I’m unintentionally filtering out elements!”, so I really appreciate that they’ve added strict generators. Perhaps I appreciate the subtle syntax difference a little less.

I wonder if/how this will show up in Elixir. Adding new syntax isn’t exactly ideal, but this is per generator, so an option to for also doesn’t fit. Has there been discussions elsewhere of how to fit strict generator’s into Elixir’s for comprehensions?

I found a discussion on the elixir-core mailing list from 2021. JosĂ© doesn’t like the idea of new operators, and there is some discussion of a for! strict comprehension, but that would mean an all-or-nothing approach to strict generators.

I’m not looking for a discussion on how strict generators could be added, but rather asking if anyone knows of plans to adopt this feature from OTP 28 into Elixir.

3 Likes