5. Data shapes

The data-ownership-v1 profile in Zryna 0.2.1 at 841c8aee901782c9f7bf442bfe8eb2fe6b7f6446 adds the published aggregate and owned-data surface. Its exact boundary is M3_PUBLIC_PROFILE.md.

Struct fields

interface Pair extends ZrynaStruct { left: i32; right: i32; }
export function score(left: i32, right: i32): i32 { const pair: Pair = Pair({ left, right }); return pair.left * 31 + pair.right; }

Pair({ ... }) is the profile’s nominal struct construction syntax. It is not a class constructor and does not grant methods or inheritance.

& $zryna run src/pair.zry --project-root "$workspace\tutorial-ownership" --profile data-ownership-v1 --target javascript --name pair-1 --export score --arg=i32:2 --arg=i32:3

Expected output: javascript: i32 65.

Fixed arrays

export function score(): i32 { const values: FixedArray<i32, 3> = FixedArray<i32, 3>([7, 11, 19]); return values[0] * 100 + values[1] * 10 + values[2]; }

The length is part of the type. Running src/array.zry as score returns i32 829 on both portable targets.

Vec

function values(): i32 { let items: Vec<i32> = Vec<i32>([7, 9]); push(items, 13); const copied: Vec<i32> = clone(items); return copied[2]; }
export function score(): i32 { return values(); }

Vec<T> is growable. push mutates it, indexing performs a checked access, and clone creates a distinct owned vector. Running src/vec.zry returns i32 13.

String

export function text(): i32 { let first: String = "héllo"; const copy: String = clone(first); const moved: String = copy; first = "new"; const joined: String = concat(first, moved); return 17; }

String is owned UTF-8 data. The public CLI exposes only scalar entry results, so this example returns the scalar sentinel i32 17 after completing the owned operations; it does not print the joined string.

Enums and exhaustive matching

interface Choice extends ZrynaEnum { none: ZrynaNone; value: i32; }
export function score(value: i32): i32 { const selected: Choice = Choice.value(value); return match(selected, { "Choice.none": () => 0, "Choice.value": (item) => item * 3 }); }

Every declared variant has one arm. Running the supplied src/enum.zry wrapper with i32:11 returns i32 33.

These forms are profile-specific language constructs, not universal TypeScript or npm compatibility.

Common errors

• A Vec or fixed-array access outside its bounds produces the typed trap zryna.trap.bounds-v1. With --json, inspect results[].outcome.kind; a complete typed trap can still be an ok: true run observation.
• Owned values cannot appear in a public entry signature in 0.2.1. Keep owned work private or imported and return an i32 or bool observation.
• Non-exhaustive enum matching is rejected.

Exercise

Run the supplied pair, array, vec, string, and enum entrypoints on WebAssembly with fresh names. Confirm the observations 65, 829, 13, 17, and 33.

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