Crate typewire 

Derive-based cross-language type bridging for Rust.

typewire provides the Typewire trait and a derive macro that generates platform-specific conversion methods and compile-time schema records from your Rust types. Define types once in Rust, get type-safe foreign-language bindings and declarations automatically.

Currently supported targets:

• WebAssembly (wasm32) — to_js / from_js / patch_js via wasm-bindgen, with TypeScript .d.ts generation
• Kotlin and Swift — planned

Quick start

use typewire::Typewire;

#[derive(Typewire)]
#[typewire(rename_all = "camelCase")]
struct CreateUser {
  user_name: String,
  age: u32,
  email: Option<String>,
}

// Option<T> fields implicitly default to None when absent
assert_eq!(<Option<String>>::or_default(), Some(None));

// Non-optional types have no implicit default
assert!(String::or_default().is_none());

On wasm32, this generates conversions matching the serde wire shape ({ "userName": ..., "age": ..., "email": ... }), plus a patch_js that updates foreign objects in place by diffing only changed fields.

Pipeline

#[derive(Typewire)]  →  encode (link section)  →  decode  →  declarations
     (derive)             (typewire-schema)        (CLI)      (codegen)

1. #[derive(Typewire)] analyzes types and emits platform-gated conversion methods + schema records in link sections (when the schemas feature is enabled)
2. The typewire CLI extracts schema records from compiled binaries and generates typed declarations for the target language
3. The generated declarations match the wire format of the Rust types

Built-in type implementations

Category	Types
Booleans	bool
Integers	i8, i16, i32, u8, u16, u32 (exact)
Big integers	i64, u64, i128, u128, isize, usize
Floats	f32, f64
Strings	String, Cow<str>, char
Unit	()
Options	Option<T>
Sequences	Vec<T>, [T; N]
Maps	HashMap, BTreeMap
Tuples	(A, B, ...) up to 12 elements
Smart pointers	Box<T>, Arc<T>, Rc<T>

With optional features: uuid, chrono, url, bytes, indexmap, serde_json, fractional_index.

Features

Feature	What it enables
derive (default)	Re-exports #[derive(Typewire)]
schemas	Embeds schema records in link sections for codegen
uuid	Typewire impl for uuid::Uuid
chrono	Typewire impl for chrono::DateTime
url	Typewire impl for url::Url
bytes	Typewire impl for bytes::Bytes
indexmap	Typewire impls for IndexMap / IndexSet
base64	base64_encode / base64_decode helpers
serde_json	Typewire impl for serde_json::Value
cli	Binary target for schema extraction + declaration generation

Re-exports

pub use typewire_schema as schema;

Enums

Error

Conversion errors produced during foreign-language value decoding.

Traits

Typewire

Bidirectional conversion between Rust types and foreign-language values.

Functions

base64_decode

Base64-decode a string to bytes using the standard alphabet.

base64_encode

Base64-encode bytes to a string using the standard alphabet.

Derive Macros

Typewire

Derive macro for the Typewire trait.