Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

See UPGRADE.md for additional help when upgrading to newer versions.

0.37.1 - 2025-09-10

Fixed

Fix required Elixir version (>= 1.15) in rustler_mix
Fix missing chdir in rustler_mix when compiling in a subdirectory (#706)

0.37.0 - 2025-09-09

Added

Add staticlib feature to compile without nif_init and add {pkg}_nif_init symbol (#688)
Add IntoIterator to OwnedBinary (#702, thanks aDifferentJT)

Fixed

Set ErlNifEntry.min_erts to a placeholder value (#703)

Changed

Refactor build logic to remove TOML dependency (#691)
Use inline on commonly used functions (#475, thanks @joshuataylor)
Make EnifAllocator available even if the allocator feature is not enabled

0.36.2 - 2025-06-09

Added

std::hash::Hash implementation for atoms (#695)

Fixed

Fix typing error in rustler_mix (#696, thanks @dkuku)

0.36.1 - 2025-02-03

No changes in the Rust code, only rustler_mix adjustments and dependency updates.

Added

Support for Erlang-style NIF module names (:module_name) (#682)

Fixed

Retrieve the newest Rustler version without additional dependencies (#682, fixes #680)
Adjust .gitignore handling to match the new workspace style

Changed

Only depend on libloading on non-Windows systems (#677)

0.36.0 - 2025-01-13

Added

Create a workplace Cargo.toml file with mix rustler.new (#672)

Fixed

Some derive macros failed when only decode was requested (#676)

Removed

The linkage override for macOS is not needed anymore and has been removed from the template (#672)

[0.35.1] - 2024-12-18

Fixed

Fix clippy lints in rustler_codegen (#671)
Adjust Rustler macros to not produce warnings on Elixir 1.18 (#670)

[0.35.0] - 2024-10-15

Added

The resource type name can be overridden with #[register_impl(name = "...")] (#638)
Floats can be decoded from integers (#641, fixes #603)
Resource types can implement and use dynamic calls on NIF version 2.16 (#635)
Encoder and Decoder implementations for Box<T> (#644)
Reference type and env.make_ref() function (#657)

Fixed

The optional register attribute on #[register_impl] works as advertised now (#638)
API functions for Windows are correctly assigned for NIF version 2.15 and above (#635)
Panics in encoding the result of NIF function are caught (#656)
Reverted change to "recompile if the NIF library is changed/deleted" (#654, fixes #651)

Changed

The special ok/error handling for atoms in serde is now restricted to variant names (#639)
rustler_sys as a separate library is merged into rustler::sys and will not be released independently of rustler anymore (#653)

[0.34.0] - 2024-07-09

Added

Resource type registration has been refactored to eventually remove the rustler::resource! macro (#617, necessary due to a pending deprecation of a Rust feature, #606)
Resources can (and should) now explicitly implement the new Resource trait and provide a custom destructor function that is run before drop and receives an Env parameter (#617)
Process monitoring via resources can now be used on resource types that implement the Resource::down callback (#617)
Resource implementation and registration helper attribute (#627)

Fixed

Unwinding in the on_load callback is now caught and leads to a panic (#617)

Changed

NIF implementations are now discovered automatically and the respective argument of rustler::init! is ignored (#613)
The derive feature flag is now ignored and its functionality unconditionally enabled (#621)

[0.33.0] - 2024-05-29

Added

Optional support for using Erlang's allocator as Rust's global allocator (#580).
Comparison functions for PIDs (#611).
Conversions from and to Rust paths (PathBuf and Path) (#608).

Fixed

mix compile failing on path dependencies in the Rust library (#577, fixed in #578 and #607)

Changed

Drop usage of lazy_static in favour of std::sync::OnceLock. This change raises the minimal supported Rust version to 1.70.
Drop obsolete and incorrect Rustler.nif_versions function.

Removed

The old macros rustler_export_nifs!, rustler::rustler_atoms! and resource_struct_init! have been removed (#604). They had been deprecated since version 0.22.0.

[0.32.1] - 2024-03-21

Added

Map iterators are now DoubleEndedIterators (#598), thus allowing being iterated in reverse using .rev()
Env::is_process_alive and LocalPid::is_alive (#599)
Encoding and decoding of 128 bit integers (#600)
Optional codec for num_bigint::BigInt using the big_integer feature (#601)
Add experimental serde support derived from serde_rustler

Changed

Adjust C char types to use the proper FFI type (#592)
Allow arbitrary (ASCII) NIF function names (#593, idea and initial implementation by @KoviRobi)

Removed

rustler_bigint is replaced by a feature flag and the wrapper is not necessary anymore (#601)

[0.32.0] - 2024-03-20

Yanked because it did not include all merged changes.

[0.31.0] - 2024-02-13

Added

Support for generic types in derive macros (#574)
New is_float and is_integer methods on terms (#581)

Fixed

Finalized making :rustler a compile-time-only dependency (#570)
Make get_type work as documented for 0.30 (#581)
Tests on ARM64 (#584)
Error messages in codegen (#579)

Changed

Use impl Encoder on more functions (in particular on send) (#572)
The generated atom modules for derived structs are now called rustler_atoms_{struct_name_in_snakecase} to silence warnings (#585)

Removed

Support for initmacro in rustler-sys (v2.3.2, #589)

[0.30.0] - 2023-10-11

Added

Return Result<(), SendError> from all send functions (#239, #563)

Changed

Deprecate :rustler_crates project configuration
Mark use Rustler module configuration as compile-time
Bump Rust edition to 2021
Make :rustler a compile-time-only dependency (#516, #559)
Use enif_term_type to implement Term::get_type (#538). Please check the UPGRADE documentation for necessary code changes.
Raise default NIF version to 2.15

Removed

Support for RUSTLER_NIF_VERSION, NIF version requirements have to be set via features now

[0.29.1] - 2023-06-30

Fixed

Exclude directories from external resources for compatibility with Elixir 1.15 (#548, thanks @adrienmo)
Fix NifTaggedEnum derived Encoder impl for named-field variants (#547, thanks @dylanburati)
Remove cfg! directives in build.rs causing cross-compilation to fail (#555, thanks @fabriziosestito)

[0.29.0] - 2023-06-22

Added

ErlOption<T> to provide an ergonomic option type for Erlang (#507, thanks @tatsuya6502)

Changed

Use Cargo features to define the NIF version level (#537), deprecating RUSTLER_NIF_VERSION

[0.28.0] - 2023-04-24

Added

Support OTP 26 (#526, thanks @philss)
Support tuples in NIF macro (#520, #527, thanks @denumerate and @philss)
Support for load_data_fun to compute load_data at runtime (#413, thanks @kaaboaye)

Changed

Enhanced NIF macro error messages for invalid attributes (#525, thanks @philss)

[0.27.0] - 2023-01-17

Added

ResourceArc::make_binary for safe use of enif_make_resource_binary (#487)
OwnedBinary is now Sync (#493)
Specified MSRV to be 1.56.1.

Changed

MIX_ENV is no longer considered for determining the build profile. Now, the profile defaults to :release. Use the :mode option to pick another profile explicitly. (#496)
Edition 2021 for the rustler mix template (#512, thanks @ayrat555)

Fixed

Documentation for load (#501, thanks @ishitatsuyuki)

[0.26.0] - 2022-09-02

Highlight

TaggedEnum

We added TaggedEnum, which is a generalized enum type (#440, thanks to @SeokminHong!). Example:

#[derive(NifTaggedEnum)]
pub enum TaggedEnum1 {
    Named { x: i32, y: i32 },
    String1(String),
    String2(String),
    Untagged,
}

On the Elixir side, the variants are represented as two-tuples {tag::atom(), inner::term()} | atom(), where the inner term is

a map for the variant Named in the example above
a binary for the String1 and String2 variants

The Untagged variant is represented as the atom :untagged in Elixir.

Added

Added Clone and Copy for TermType (#476, thanks @dvic)
Added Env.whereis_pid() (#456, thanks @Qqwy)

Changed

Use &[impl Encoder] for keys and values in map_from_arrays() to improve ergonomics (#453, thanks @SeokminHong)
Improved encode/decode performance of TaggedEnum considerably (#482, thanks @cleaton)
Test on OTP 25 (#455)

Fixed

Lifetime handling in rustler_codegen (#483, thanks @turion @SeokminHong and @neosimsim)
Support multiple variants with same field names in TaggedEnum (#482, thanks @cleaton)
Support .toml file extension for cargo config (#468, thanks @joshuataylor for the report in #467)
Disambiguate encode/decode in generated code (#466, thanks @SeokminHong)
Migrate CI to erlef/setup-beam (#457, thanks @SeokminHong)
Documentation of the schedule flag for nif macro (#444)
Improve documentation (#429, thanks @turion)

[0.25.0] - 2022-04-11

Added

NewBinary now also available as rustler::NewBinary (thanks @ayrat555)
Term::map_from_pairs() to conveniently build a map from a list of pairs (thanks @philss)
CI now also tests against macos

Fixed

Snake-case warening for auto-generated RUSTLER_{}_field_{} variables (renamed to rustler_{}_field_{})

Changed

Abort compilation on macos if macos target configuration is missing

[0.24.0] - 2022-02-24

Added

A NewBinary type to create binaries in Rust without going through OwnedBinary. This can improve performance. Thanks @dlesl!
TermType derives Eq and PartialEq.

Fixed

Set library file extension based on the compile target, thanks @cocoa-xu!
Relaxed Jason version requirement to ~> 1.0
Various typos in the documentation, thanks @kianmeng!

Changed

Rustler supports the latest 3 versions of Elixir and OTP. Currently, those are Elixir => 1.11 and OTP >= 22.
rustler_mix: Bumped required toml dependency to 0.6
Bumped rustler_sys dependency to ~2.2

[0.23.0] - 2021-12-22

Added

NifException for using Elixir exception structs
Hashing for term
Hash and Equality for Binary and OwnedBinary

Fixed

mix rustler.new with Elixir v1.13
Template config for macos
Crash if metadata cannot be retrieved while compiling (#398)

Changed

Rustler changed its supported range of OTP and Elixir versions. We aim to support the three newest versions of OTP and Elixir.
The decoder for Range requires that :step equals 1. The :step field was introduced with Elixir v1.12 and cannot be represented with Rust's RangeInclusive.
NIF API bindings are generated using Rust

[0.22.2] - 2021-10-07

Fixed

Fixed a regression introduced with #386: Rustler.Compiler.Config called into cargo when skip_compilation? was set, breaking setups where cargo is not installed. Fixed with #389, thanks @karolsluszniak

[0.22.1] - 2021-10-05

Fixed

[Breaking change] codegen-generated decoders always raise an error instead of causing the calling NIF to return an atom in some cases
Fix codegen problem for untagged enums (#370)
Fix handling local dependencies with @external_resources (#381)

[0.22.0] - 2021-06-22

Added

Simple Debug impl for rustler::Error
Support newtype and tuple structs for NifTuple and NifRecord
rustler::Error::Term encoding an arbitrary boxed encoder, returning {:error, term}
Generic encoder/decoder for HashMap<T, U>, where T: Decoder and U: Decoder

Fixed

Compilation time of generated decoders has been reduced significantly.
Fixed a segfault caused by OwnedEnv::send_and_clear

Changed

Renamed Pid to LocalPid to clarify that it can't point to a remote process
Dependencies have been updated.
Derive macros have been refactored.
Macros have been renamed and old ones have been deprecated:
- rustler_export_nifs! is now rustler::init!
- rustler_atoms! is now rustler::atoms!
- resource_struct_init! is now rustler::resource!

New rustler::atoms! macro removed the atom prefix from the name:

//
// Before
//
rustler::rustler_atoms! {
    atom ok;
    atom error;
    atom renamed_atom = "Renamed";
}

//
// After
//
rustler::atoms! {
    ok,
    error,
    renamed_atom = "Renamed",
}

NIF functions can be initialized with a simplified syntax:

//
// Before
//
rustler::rustler_export_nifs! {
    "Elixir.Math",
    [
        ("add", 2, add)
    ],
    None
}

//
// After
//
rustler::init!("Elixir.Math", [add]);

NIFs can be derived from regular functions, if the arguments implement Decoder and the return type implements Encoder:

//
// Before
//
fn add<'a>(env: Env<'a>, args: &[Term<'a>]) -> Result<Term<'a>, Error> {
    let num1: i64 = args[0].decode()?;
    let num2: i64 = args[1].decode()?;

    Ok((atoms::ok(), num1 + num2).encode(env))
}

//
// After
//
#[rustler::nif]
fn add(a: i64, b: i64) -> i64 {
  a + b
}

rustler::nif exposes more options to configure a NIF were the NIF is defined:


#[rustler::nif(schedule = "DirtyCpu")]
pub fn dirty_cpu() -> Atom {
    let duration = Duration::from_millis(100);
    std::thread::sleep(duration);

    atoms::ok()
}

#[rustler::nif(name = "my_add")]
fn add(a: i64, b: i64) -> i64 {
  a + b
}

Deprecated

The rustler compiler has been deprecated and will be removed with v1.0. NIFs are no longer defined in mix.exs, but are configured with use Rustler. See the documentation for the Rustler module. To migrate to the new configuration:

Drop :rustler from the :compilers key in your mix.exs project/0 function
Drop :rustler_crates from project/0 and move the configurations into the use Rustler of your NIF module or application config:
```
# config/dev.exs
config :my_app, MyApp.Native,
  mode: :debug
```

For more information, see the documentation.

[0.21.0] - 2019-09-07

Added

Support for OTP22.
Rust linting with clippy.
Support for decoding IOLists as binaries, Term::decode_as_binary.

Changed

rustler_codegen is now reexported by the rustler crate. Depending on the rustler_codegen crate is deprecated.
erlang_nif-sys has been renamed to rustler_sys and vendored into the rustler repo.
Replaced the hand-rolled TOML parser in rustler_mix with the toml-elixir package.
Improve error messages for derived encoders/decoders.
Rust bool now corresponds only to booleans (false, true) in Elixir. Previously, nil and false were both decodable to bool. To use the previous behaviour, a Truthy newtype was introduced.

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