feat(Stream): add Stream.onStart api

[dilame]

Not sure about name, maybe it should be tapSubscribe?

Type

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update

Implement Stream.tapStart that adds an effect to be executed at the start of the stream.

import { Console, Effect, Stream } from "effect";

const stream = Stream.make(1, 2, 3).pipe(
  Stream.tapStart(Console.log("Stream started")),
  Stream.map((n) => n * 2),
  Stream.tap((n) => Console.log(`after mapping: ${n}`))
) 

Effect. runPromise(Stream. runCollect(stream)).then(console. log) 
// Stream started 
// after mapping: 2 
// after mapping: 4 
// after mapping: 6 
// { _id: 'Chunk', values: [ 2, 4, 6 ] }

[changeset-bot]

🦋 Changeset detected

Latest commit: 79e501d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 31 packages

Name	Type
effect	Minor
@effect/cli	Major
@effect/cluster-browser	Major
@effect/cluster-node	Major
@effect/cluster-workflow	Major
@effect/cluster	Major
@effect/experimental	Major
@effect/opentelemetry	Major
@effect/platform-browser	Major
@effect/platform-bun	Major
@effect/platform-node-shared	Major
@effect/platform-node	Major
@effect/platform	Major
@effect/printer-ansi	Major
@effect/printer	Major
@effect/rpc-http	Major
@effect/rpc	Major
@effect/schema	Major
@effect/sql-d1	Major
@effect/sql-drizzle	Major
@effect/sql-kysely	Major
@effect/sql-mssql	Major
@effect/sql-mysql2	Major
@effect/sql-pg	Major
@effect/sql-sqlite-bun	Major
@effect/sql-sqlite-node	Major
@effect/sql-sqlite-react-native	Major
@effect/sql-sqlite-wasm	Major
@effect/sql	Major
@effect/typeclass	Major
@effect/vitest	Major

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[dilame]

Done. What do you think about Stream.onEnd with concat(self, drain(fromEffect(effect)))?

[tim-smart]

Done. What do you think about Stream.onEnd with concat(self, drain(fromEffect(effect)))?

I'm OK with it. Feel free to open a seperate PR.