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# Alef
<div align="center" style="display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; margin: 20px 0;">
<a href="https://crates.io/crates/alef">
<img src="https://img.shields.io/crates/v/alef?label=Crates.io&color=007ec6" alt="Crates.io">
</a>
<a href="https://docs.rs/alef">
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</a>
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<a href="https://www.rust-lang.org">
<img src="https://img.shields.io/badge/Rust-1.99%2B-007ec6?logo=rust&logoColor=white" alt="Rust 1.99+">
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<a href="#supported-targets">
<img src="https://img.shields.io/badge/Targets-18-007ec6" alt="18 targets">
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<div align="center" style="margin: 28px 0 18px;">
<div style="font-size: 72px; line-height: 1;">א</div>
<strong>Rust in. Native bindings out.</strong>
</div>
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<a href="https://github.com/xberg-io/alef">
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Alef is the polyglot binding generator behind the xberg.io ecosystem. It extracts a Rust API surface
and emits language-native bindings, package scaffolding, type stubs, README files, API docs, e2e
tests, and release metadata from one `alef.toml`.
**[Installation](#installation)** | **[Quick Start](#quick-start)** | **[Supported Targets](#supported-targets)** |
**[CLI Reference](#cli-reference)**
## Key Features
- **One source of truth** - Configure a Rust workspace once and generate every enabled language target from it.
- **Language-native bindings** - Emit host-language types, docs, errors, async wrappers, callbacks, and package files.
- **Multi-crate workspaces** - Drive multiple independently published binding packages from a shared workspace config.
- **End-to-end fixtures** - Generate cross-language test suites and registry-mode test apps from shared JSON fixtures.
- **Release-aware packaging** - Sync versions, generate registry metadata, build artifacts, and validate publication state.
- **Configurable pipelines** - Run setup, update, format, lint, test, clean, build, and publish commands per language.
- **Pluggable extension surface** - Author domain-specific codegen logic via the `Extension` trait; ship as linked binaries, dynamic libraries, or template-only declarations.
- **Staleness checks** - Cache inputs, embed generation hashes, and verify whether generated files are up to date.
## Installation
Alef requires Rust 1.99 or newer. To build from source:
```bash
cargo install alef --locked
```
[`cargo-binstall`](https://github.com/cargo-bins/cargo-binstall) avoids compiling Alef when a
matching published artifact is available. It still requires Cargo and falls back to
`cargo install` from source when no compatible artifact is available:
```bash
cargo binstall alef
```
Homebrew installs a bottle when one is available and otherwise may build the formula from source:
```bash
brew install xberg-io/tap/alef
```
Scoop installs the published Windows binary:
```powershell
scoop bucket add xberg https://github.com/xberg-io/scoop-bucket
scoop install alef
```
## Quick Start
Create or edit `alef.toml` in your Rust workspace:
```toml
[workspace]
languages = ["python", "node", "ffi", "go"]
alef_version = "0.79.2"
[[crates]]
name = "sample_core"
sources = ["src/lib.rs"]
version_from = "Cargo.toml"
```
Then generate the language packages:
```bash
alef generate --format
alef scaffold
alef readme
alef docs --output docs/reference
alef verify
```
For a new project, Alef can create the initial config and first generated files:
```bash
alef init --lang python,node,ffi
```
For the full local generation pass, use:
```bash
alef all --format
```
Use `--lang python,node` on language-aware commands such as `generate` and `build` to select targets.
`verify` checks the complete generated surface. Use `--crate <name>` to restrict commands to one configured crate.
## Supported Targets
| Target | Backend / package style |
| ------ | ----------------------- |
| Python | PyO3 bindings with Python type stubs |
| TypeScript / Node.js | NAPI-RS native addon with `.d.ts` output |
| WebAssembly | wasm-bindgen package for browser and JS runtimes |
| Ruby | Magnus native extension |
| PHP | Native PHP extension |
| Elixir | Rustler NIF package |
| R | extendr package |
| Go | cgo package over the generated C FFI layer |
| Java | JVM package over the generated native library |
| Kotlin | Kotlin/JVM package over generated native bindings |
| Kotlin Android | Android package with generated JNI shims |
| C# | .NET package using P/Invoke |
| Dart / Flutter | flutter_rust_bridge package |
| Swift | Swift package with Rust bridge support |
| Zig | Zig package over the generated C ABI |
| Gleam | Gleam package backed by Rustler |
| C FFI | C ABI, header, and shared-library glue |
| JNI | Rust JNI shim crate exercised by both kotlin_android (Android AAR) and host-JVM tests |
Canonical language slugs are `python`, `node`, `wasm`, `ruby`, `php`, `elixir`, `r`, `go`,
`java`, `csharp`, `kotlin`, `kotlin_android`, `swift`, `dart`, `gleam`, `zig`, `ffi`, and `jni`.
## Configuration Model
Alef uses the current multi-crate schema:
- `[workspace]` stores shared target languages, tool preferences, and pipeline defaults.
- `[[crates]]` describes each Rust API surface that should become one or more published packages.
- `[crates.<language>]` sections customize module names, package names, feature flags, output paths,
field naming, dependency extras, and language-specific generation behavior.
- `[[crates.adapters]]`, trait bridge config, service API config, and e2e config opt into higher-level
generated wrappers when a target supports them.
Generated binding files carry Alef hashes and are overwritten by generation commands. Scaffolded
package files are generated once unless the command explicitly opts into overwrite behavior; generated
README and API doc files are owned by `alef readme` and `alef docs`.
### Cargo Package Archives
Generated Rust crates can use Cargo's native package allowlist or denylist:
```toml
[workspace.package_metadata.cargo]
include = ["src/**", "build.rs", "!src/**/tests.rs"]
```
Use `exclude` instead of `include` for a denylist. Alef rejects configuring both because Cargo treats
`include` as overriding `exclude`. Patterns remain ordered and crate-relative. A
`[crates.package_metadata.cargo]` table replaces the workspace table for that crate, and an empty
crate table clears the inherited filters.
### Transparent String Wrappers
A core type that deliberately hides its string value from `Display` can still be exposed as a
plain string in every binding. Mark the wrapper with explicit conversion operations:
```rust
#[derive(Clone)]
#[cfg_attr(alef, alef(transparent_string(from = "from", into = "into_inner")))]
pub struct SecretString(String);
impl SecretString {
pub fn from(value: String) -> Self { Self(value) }
pub fn into_inner(self) -> String { self.0 }
}
```
The wrapper is omitted from generated binding APIs. Alef calls `SecretString::from(String)` when a
binding value enters Rust and consumes the wrapper with `SecretString::into_inner()` when a core
value leaves Rust. Both operations must be public synchronous inherent methods with the exact
signatures shown above. The wrapper must implement `Clone`: generated FFI getters clone an owned
wrapper before calling the consuming `into` method. Alef reports invalid annotations, shapes, or
methods as unsupported public-item diagnostics and never falls back to `Display` or `ToString`.
Binding-visible wrappers must also have unique short type names; Alef reports same-named wrappers
from different modules as ambiguous instead of attaching one module's conversion to the other.
The conversion metadata is preserved through struct and enum fields, parameters and returns,
including nested `Option`, `Vec`, and map keys and values. Rust-backed shared generators, Dart's
bridge crate, and the C FFI layer apply the conversion; Zig and Gleam inherit it through that FFI
layer. The emitted-tree compile gate covers FFI, Python, Node, Wasm, and JNI. PHP is text-gated
because its Rust crate needs PHP headers. Dart has direct conversion-generator tests; R, Zig, and
Gleam do not yet have an annotation-specific downstream toolchain build.
### Sensitive Fields
Mark a struct field, an enum variant, or a field of an enum variant that holds a credential so
generated representations never print it:
```rust
pub struct Credentials {
pub label: String,
#[cfg_attr(alef, alef(sensitive))]
pub token: String,
}
```
The flag only changes human-readable representations. Serialization and deserialization stay
lossless: `serde_json` and every conversion between the binding and the core type still carry the
real value.
| Backend | Effect |
|---------|--------|
| Python (PyO3) | Dataclass fields are generated with `field(repr=False)`, so `repr()` and `str()` omit them while `dataclasses.asdict()` keeps them. Data enums with a sensitive field or variant return `Name(<redacted>)` from `__str__` and `__repr__` instead of serializing the payload. |
| Ruby (Magnus), Elixir (Rustler) | The Rust-side binding type drops `derive(Debug)` and gets a `Debug` impl that prints `<redacted>` for sensitive fields (the whole value for a sensitive enum variant). |
| Kotlin | A sensitive positional field of an error variant is rendered as `<redacted>` in the generated exception message. |
The remaining backends (NAPI, WASM, extendr, Swift, Go, Java, C#, and the others) do not yet honour
the flag; their generated types and `toString`/`Debug`-style output still print every field. Error
messages produced by the core crate's own `Display` implementation are never rewritten, so a
`#[error("... {0}")]` template that prints a sensitive field is the core crate's responsibility.
Elixir protection is incomplete: complete protection for ordinary tuple representations would
need a later, breaking change to the Elixir representation.
## Downloadable Native Components
Alef can split fixed Cargo feature profiles into signed native components instead of putting every
feature combination in every wheel. A component is the deployable unit -- one Cargo feature set
built into one signed prebuilt artifact per target -- modelled on Python extras but
language-neutral; it *provides* one or more contracts. A contract is an explicitly selected Rust
trait; Alef generates a versioned C function table for it, one producer entrypoint per contract in
the component's `cdylib`, and a host runtime. Component implementation types currently construct
through `Default`. Only C-compatible scalar, UTF-8, byte-buffer, and opaque-handle representations
cross the dynamic-library boundary—never Rust trait objects or Rust-owned layouts. A component's
version always tracks the core crate's version; components are not versioned independently.
```toml
[[crates.component_contracts]]
name = "engine"
trait_path = "my_core::Engine"
interface_version = 1
[[crates.components]]
name = "cuda"
provides = [{ contract = "engine", implementation = "my_core::CudaEngine" }]
features = ["cuda"]
default_features = false
# Optional: defaults to every supported target enabled by [targets], minus bundled_on.
targets = ["x86_64-unknown-linux-gnu", "aarch64-apple-darwin"]
# Optional: targets/platforms where downloading is unsupported and the component must
# instead be linked into the binding (not yet implemented by any backend).
bundled_on = []
[component_distribution]
url_template = "https://downloads.example.com/{component}/{version}/{target}/{artifact}"
[component_distribution.public_keys]
release-2026 = "BASE64_ENCODED_32_BYTE_ED25519_PUBLIC_KEY"
```
`[component_distribution]` may also be set per crate as `[crates.component_distribution]`, which
overrides the workspace default field by field (a crate-level `url_template` replaces the workspace
one; a crate-level public key overrides a workspace key with the same ID, and workspace-only keys
are kept). A component may provide more than one contract; a component provides each contract at
most once, though the same contract may be provided by more than one component under different
feature sets.
Generate/scaffold first, then build and sign each configured target in CI:
```console
alef scaffold
alef component build
alef component package --signing-key "$CI_ED25519_PRIVATE_KEY_FILE" --key-id release-2026
alef component verify
alef component lock
```
The private Ed25519 key stays in protected CI secret storage. It signs canonical component manifests;
it does not encrypt the binary. Generated native binding packages compile in the contents of
`components.lock.json`, including the public verification keys, but do not contain the component
libraries. Each supported binding exposes idiomatic `load`, `prefetch`, `status`, and `cache path`
operations. The runtime selects the exact target, downloads on demand, verifies the pinned size,
SHA-256 digest, and Ed25519 signature, installs under a cache lock, validates the
ABI/contract/feature identity, and keeps the library loaded for the process lifetime.
| Component host surface | Bindings |
| ---------------------- | -------- |
| Direct native runtime | Python, Node.js, Ruby, PHP, Elixir, R, Dart/FRB, Swift |
| Shared generated C manager | C FFI, Go, Java, Kotlin/JVM, C#, Zig, Dart/FFI |
| Rustler manager | Gleam |
| Explicitly unsupported | WebAssembly, Kotlin Android, Android JNI, Apple mobile targets |
Unsupported bindings still generate the four management operations, but each operation returns a
clear platform error instead of silently omitting the API. Rust callers can use
`alef-component-runtime::ComponentManager` directly.
The initial loader supports x86-64 and ARM64 Linux GNU, x86-64 and ARM64 macOS, and x86-64 Windows
MSVC. Mobile and WebAssembly targets are intentionally excluded because they do not provide the same
dynamic-loading model.
## Extending Alef
Alef is opinionated about codegen and neutral about domain. The `Extension` trait lets you ship domain-specific generation logic (HTTP service APIs, plugin registries, custom bindings) without bloat in alef.
### Linked Extension
Consumer crate implements `alef::Extension`, ships a thin CLI binary:
```rust
fn main() {
alef::run_with_extensions(vec![Box::new(MyDomainExtension)])
}
```
Full type safety. Recommended for frameworks that generate an HTTP service API.
### Dynamic Extension
Load a compiled `.so`/`.dylib`/`.dll` declaring a C-ABI factory function. Works when you can't ship a Rust binary.
```toml
[[extensions.dylib]]
path = "target/release/libmy_extension.dylib"
```
```rust
extern "C" fn alef_extension_factory() -> Box<dyn alef::Extension> {
Box::new(MyExtension)
}
```
### Template-only Extension
Declare `[[extensions.template]]` blocks in `alef.toml` pointing to Jinja templates. Alef's built-in `TemplateExtension` emits them — no Rust required.
The full extension walkthrough covers trait references and per-language emission patterns.
## CLI Reference
| Command | Purpose |
| ------- | ------- |
| `alef init` | Create `alef.toml`, generate initial bindings, and scaffold package files. |
| `alef extract` | Extract Rust source into Alef IR JSON. |
| `alef generate` | Generate bindings, service API wrappers, public API wrappers, and type stubs. |
| `alef stubs` | Generate type stubs only. |
| `alef scaffold` | Generate package manifests, native build files, and package scaffolding. |
| `alef readme` | Generate per-language README files. |
| `alef docs` | Generate Markdown API reference pages. |
| `alef setup` | Install per-language development dependencies. |
| `alef fmt` / `alef lint` | Run configured formatters, linters, and type checks. |
| `alef test` | Run configured unit, integration, e2e, or coverage test commands. |
| `alef build` | Build language bindings using native tools. |
| `alef verify` | Check generated output freshness and completeness for CI; use `alef build` and `alef lint` separately. |
| `alef diff` | Show what generation would change without writing files. |
| `alef schema` | Write or `--check` a vendored copy of the `alef.toml` JSON Schema. |
| `alef e2e` | Initialize, scaffold, validate, list, or generate local e2e suites. |
| `alef test-apps` | Generate and run standalone registry-mode test applications. |
| `alef publish` | Prepare, build, package, and validate release artifacts. |
| `alef component` | Build, package, verify, and lock downloadable runtime components. |
| `alef all` | Run the full generation workflow in one command. |
Run `alef --help` or `alef <command> --help` for the full option set.
### Vendoring the `alef.toml` JSON Schema
`schemas/alef.schema.json` is Alef's own config schema — the JSON Schema for `alef.toml` — which
you may vendor so an editor can validate `alef.toml` offline. It is **not** a generated binding:
nothing in `alef generate`, `alef build`, or `alef all` writes or refreshes it, and no build step
reads it. Alef never creates the file on its own; run `alef schema` explicitly if you want a copy:
```bash
alef schema --output schemas/alef.schema.json # write or refresh
alef schema --check # byte-exact staleness check
```
If a copy exists at the default path, `alef verify` reports it. A copy that describes a different
`alef.toml` surface than the running Alef fails verification, because an editor validating against
it is answering for a different release. A copy whose only difference is the embedded version stamp
is reported as informational and does not fail — the described config surface is unchanged, so
editor validation is still correct.
## Development
This repository uses `mise` tasks for common workflows:
```bash
mise run setup
mise run build
mise run test
mise run lint
```
The most useful targeted commands while working on Alef itself are:
```bash
cargo test <module_or_test_name>
cargo insta review
prek run --all-files
```
## Part of Xberg.io
- [Xberg](https://github.com/xberg-io/xberg) — the open-source content-intelligence engine: text, tables, and metadata from 101 formats (115 file extensions), with OCR, transcription, and code intelligence. MIT.
- [Xberg Pro](https://xberg.io) — a complete self-hosted content-intelligence backend in a single container. Commercial.
- [Xberg Enterprise](https://xberg.io) — the distributed, governed content-intelligence platform, scaled on Kubernetes with team governance and support. Commercial.
- [crawlberg](https://github.com/xberg-io/crawlberg) — web crawling and scraping with HTML→Markdown and headless-Chrome fallback.
- [html-to-markdown](https://github.com/xberg-io/html-to-markdown) — fast, lossless HTML→Markdown engine.
- [liter-llm](https://github.com/xberg-io/liter-llm) — universal LLM API client with native bindings for 14 languages and 165 providers.
- [tree-sitter-language-pack](https://github.com/xberg-io/tree-sitter-language-pack) — tree-sitter grammars and code-intelligence primitives.
- [alef](https://github.com/xberg-io/alef) — the polyglot binding generator that produces every per-language binding across the 5 polyglot repos.
- [Discord](https://discord.gg/xt9WY3GnKR) — community, roadmap, and release discussion.
## License
MIT - see [LICENSE](LICENSE) for details.