Rust

One projector: rust-serde.ts, TypeRef → idiomatic Rust structs/enums with serde derives. IR field names are wire-format strings (arbitrary camelCase/kebab-case); the projector converts to Rust's conventional snake_case and emits #[serde(rename = "...")] whenever the converted form doesn't round-trip, keeping the Rust identifier idiomatic while the wire representation stays byte-for-byte unchanged.

serde

import { toRust } from "@rhi-zone/fractal-type-ir/rust"
// or: import { toRust } from "@rhi-zone/fractal-type-ir/rust-serde"

toRust(t(types.object({
  id: t(types.string),
  name: t(types.string),
  email: t(types.string),
  age: opt(t(types.integer)),
})), "User")

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct User {
    pub id: String,
    pub name: String,
    pub email: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub age: Option<i64>,
}

Both meta.optional (may be absent from the wire) and meta.nullable (present but may be null) collapse onto the same Option<T> + #[serde(skip_serializing_if = "Option::is_none")] — serde's convention doesn't distinguish "missing key" from "explicit null" the way the IR's two flags do.