@raisindb/function-assemblyscript

Write a RaisinDB server function in AssemblyScript and ship it as a WebAssembly component — TypeScript-shaped syntax, no embedded JavaScript engine, artifacts measured in kilobytes.

raisindb create function greet --lang assemblyscript --ns demo
raisindb function build wasm/demo/greet
raisindb function run   wasm/demo/greet --input '{"name":"Ada"}'

Writing a handler

import { run, log, nodes, unknownHandler, cabi_realloc } from "@raisindb/function-assemblyscript";

function greet(input: string): string {
  log.info("greeting");
  const children = nodes.getChildren("content", "/pages", 50);
  return '{"greeting":"hello","pages":' + children.length.toString() + "}";
}

// The component exports ONE function; the node's `entry_file` suffix picks the
// handler, so routing is an ordinary switch.
function route(name: string, input: string): string {
  if (name == "default") return greet(input);
  return unknownHandler(name, "default");
}

export function handler(np: i32, nl: i32, ip: i32, il: i32): i32 {
  return run(np, nl, ip, il, route);
}
export { cabi_realloc };

handler and cabi_realloc must both be exported from the entry module: wasm-tools component new looks them up by name.

Why the lowering is hand-written

AssemblyScript deliberately does not implement WASI or the Component Model and has no wit-bindgen backend, so asc produces a core module while the host requires a component. assembly/abi.ts is the bridge — the only file that knows about pointers — and raisindb function build runs asc → wasm-tools component embed → wasm-tools component new.

Two ABI details it exists to get right, both of which fail silently:

• An imported interface is named with its package version, raisin:function/[email protected].
• A variant discriminant is a u8 padded to the payload's alignment, so result<string, string> is { u8 tag, 3 pad, i32 ptr, i32 len }. Read as an i32 the tag picks up padding and every Ok looks like an Err — with the payload still decoding correctly.

Strings, not objects

Handlers take and return JSON strings. AssemblyScript has no built-in JSON, and bundling one would make every artifact pay for it. Use json-as if you want typed (de)serialisation, or build strings directly for simple outputs.