cmd: ("command")

[philcockfield]

module: sys.ext.automerge

const cmd = Cmd.create<C>(doc);
const events = cmd.events(dispose$);

---

A distributed function ("command") invokation strategy using CRDT's as the underlying coordination transport to deliver the invoke (⚡️) event along with event payloads.

Then a strongly typed, elegant programming API that wraps the basic mechanic to make usage of the mechanism easy, simple, and consistent for common usecases.

• Cmd → (invoke, no response)
• Cmd → Response

---

"subroutine invocation with indirection"

"He listened to what Alan was saying and said, 'well you're not really sending messages' you're doing 'subroutine invocation with indirection' which was brilliant, that's a really brilliant idea. But what if you actually were sending messages?"

↑ Crockford on Carl Hewitt, reacting to Alan Kay and looking at SmallTalk in early 1970's at MIT — video timestamp

---

// Sample command type definitions:

type P = { a: number; b: number };
type R = { sum: number };
type E = t.CmdError & { code: number; type: 'bounds' };

type C = C1 | C2 | C3;
type C1 = t.CmdType<'add', P, C2, E>;
type C2 = t.CmdType<'add:res', R>;
type C3 = t.CmdType<'foo', { msg?: string }>;

const sum = ({ a, b }: P): R => ({ sum: a + b });

sample chained invocation call:

await cmd
  .invoke('add', 'add:res', { a: 1, b: 2 })
  .listen()
  .onError((e) => /* log error */)
  .onComplete((e) => /* success */)
  .promise();

TODO: collapse this further into strongly typed DX, for both client invokation calls, and server/handler setup.

---

↑ Cmd is an implementation of this part of the abstract system diagram

[philcockfield]

timestamp

[philcockfield]

timestamp

"...he was born on the other side of a paradigm shift, so when he talks, nobody understands what he means because he's seeing things from a completely different perspective" - Douglas Crockford

ref

[philcockfield]

"subroutine invocation with indirection"

"He listened to what Alan was saying and said, 'well you're not really sending messages' you're doing 'subroutine invocation with indirection' which was brilliant, that's a really brilliant idea. But what if you actually were sending messages?"

↑ Crockford on Carl Hewitt, reacting to Alan Kay and looking at SmallTalk in early 1970's at MIT — video timestamp