Bus.plug type ergonomics

[Antti Risteli]

Hi,

I think Bus.plug could be more ergonomic. plug seems to require type parameter for the stream being plugged into the Bus in some cases. It seems that Bus<A>.plug requires the plugged stream type B to be assignable to A and A to be assignable to B while I believe that the former would be enough. (Note: strict mode TS is required for the compile error)

import * as Bacon from "baconjs";

type TestObject = { a?: number; b?: string };
const testBus = new Bacon.Bus<TestObject>();

// these work
testBus.push({ a: 242124 });
testBus.push({ b: "jee" });

// this works:
testBus.plug(Bacon.interval(1000, 0).map<TestObject>(() => ({ a: 999 })));

// this does not compile
testBus.plug(Bacon.interval(1000, 0).map(() => ({ a: 999 })));

// type testing  done by @milankinen 
interface BBus<V> {
  plug(x: Bacon.Observable<V>): void;
  plug2<OV extends V>(x: Bacon.Observable<OV>): void;
}

const b = (testBus as any) as BBus<TestObject>;

// this compiles without errors
b.plug2(Bacon.interval(1000, 0).map(() => ({ a: 999 })));

[Juha Paananen]

This is a likely simple fix per se, but to have the whole project compile with `—strict` will take a lot of effort. I’d like to have a failing test first and then improve typings.

…

On 15 Jun 2019, at 15:21 , Antti Risteli ***@***.***> wrote: Hi, I think Bus.plug could be more ergonomic. plug seems to require type parameter for the stream being plugged into the Bus in some cases. It seems that Bus<A>.plug requires the plugged stream type B to be assignable to A and A to be assignable to B while I believe that the former would be enough. (Note: strict mode TS is required for the compile error) import * as Bacon from "baconjs"; type TestObject = { a?: number; b?: string }; const testBus = new Bacon.Bus<TestObject>(); // these work testBus.push({ a: 242124 }); testBus.push({ b: "jee" }); // this works: testBus.plug(Bacon.interval(1000, 0).map<TestObject>(() => ({ a: 999 }))); // this does not compile testBus.plug(Bacon.interval(1000, 0).map(() => ({ a: 999 }))); // type testing done by @milankinen interface BBus<V> { plug(x: Bacon.Observable<V>): void; plug2<OV extends V>(x: Bacon.Observable<OV>): void; } const b = (testBus as any) as BBus<TestObject>; // this compiles without errors b.plug2(Bacon.interval(1000, 0).map(() => ({ a: 999 }))); — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#738?email_source=notifications&email_token=AACHQZERL7MIBM47CN2QBCLP2TNFDA5CNFSM4HYO5V5KYY3PNVWWK3TUL52HS4DFUVEXG43VMWVGG33NNVSW45C7NFSM4GZWEKFQ>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AACHQZCCXZH4TQISFSU4HETP2TNFDANCNFSM4HYO5V5A>.

[Juha Paananen]

How about this: 02c28fd

[Juha Paananen]

Included in 3.0.4