feat: add support for merging external events into Prompt.custom

[lloydrichards]

Type

• Feature

Description

I've been wanting a way to link in external data into the Prompt.custom in a way that triggers a re-render without needing to press a key stroke. In the current implementation I need to fake a key stroke using process.stdin as a hack-y work around or build me own render loop from scratch. Ideally what I wanted was an API where I could just pass in a stream of events and be able to trigger the action with the next state:

const eventQueue = yield * Queue.make<number>()

const prompt = Prompt.custom(
  { count: 0 },
  {
    render: (state) => Effect.succeed(`Count: ${state.count}`),
    process: (_input, state) => Effect.succeed(Action.Submit({ value: state.count })),
    clear: () => Effect.succeed(""),
    receive: (value, state) => Effect.succeed(Action.NextFrame({ state: { count: state.count + value } })) // <-- handle events from the dequeue
  },
  Queue.asDequeue(eventQueue) // <-- provide the event queue as a dequeue to the prompt
)

I've been digging around in the Prompt.ts for a while now so I already knew the Terminal.readInput was a Queue and that it shouldn't be too hard to just merge two Queues together.

What I settled on was a type overload where there is the current implementation without the event doing the same thing (non-breaking) and the new type that adds the new events Queue.Dequeued argument and extends the handlers with the received callback. This way adding the queue can be a progressive enhancement on an already functioning user input only prompt.

Some things I needed to mull over:

• The Prompt isn't responsible for cleaning up the Queue, this needs to be handled by the user
• There is a very small possibility of an event and a user input happening simultaneously and which one is picked first is indeterministic (I think)
• Queue needs to not fail (Queue.Dequeue<A, never> so the user is responsible outside of the Prompt to handle these causes.

Related

I wanted to make an issue first but needed to open the repo to poke around in the types and next thing I know I was already halfway through implementing it 🤦‍♂️

Open to other suggestions or requests to change the approach.

[changeset-bot]

🦋 Changeset detected

Latest commit: 5b3e6bc

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

This PR includes changesets to release 27 packages

Name	Type
effect	Major
@effect/opentelemetry	Major
@effect/platform-browser	Major
@effect/platform-bun	Major
@effect/platform-node-shared	Major
@effect/platform-node	Major
@effect/vitest	Major
@effect/ai-anthropic	Major
@effect/ai-openai-compat	Major
@effect/ai-openai	Major
@effect/ai-openrouter	Major
@effect/atom-react	Major
@effect/atom-solid	Major
@effect/atom-vue	Major
@effect/sql-clickhouse	Major
@effect/sql-d1	Major
@effect/sql-libsql	Major
@effect/sql-mssql	Major
@effect/sql-mysql2	Major
@effect/sql-pg	Major
@effect/sql-pglite	Major
@effect/sql-sqlite-bun	Major
@effect/sql-sqlite-do	Major
@effect/sql-sqlite-node	Major
@effect/sql-sqlite-react-native	Major
@effect/sql-sqlite-wasm	Major
@effect/openapi-generator	Major

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[lloydrichards]

here are a couple concrete examples of where this would be used:

• log viewer <- being able to pass in streams logs to show in a scrollable viewport
• perlin flow <- add a a tickEvent which can move the animation loop along