writable_stream

The sink side of the Streams API. Build one from an underlying sink via the Builder and write into it through a Writer acquired with get_writer.

Types

Builder

opaque </>

The configuration for a WritableStream.

pub opaque type Builder(a)

WritableStream

</>

A JavaScript WritableStream — a destination for writing bytes or objects.

See WritableStream on MDN.

pub type WritableStream(a)

Values

abort

</>

pub fn abort(
  stream: WritableStream(a),
  reason reason: r,
) -> promise.Promise(Result(Nil, stream.StreamLifecycleError))

Aborts the stream. Returns Locked if the stream is locked to a writer, or Errored if the underlying sink’s abort callback throws or returns a rejecting promise.

build

</>

pub fn build(
  builder: Builder(a),
) -> Result(WritableStream(a), stream.StreamLifecycleError)

Creates a WritableStream from the configured Builder. Returns Errored if the start callback throws synchronously; the thrown value is the variant’s reason.

close

</>

pub fn close(
  stream: WritableStream(a),
) -> promise.Promise(Result(Nil, stream.StreamLifecycleError))

Closes the stream after all writes complete. Returns Locked if the stream is locked to a writer, or Errored if the underlying sink’s close callback throws or returns a rejecting promise, or if the stream is already closing or closed.

from_write

</>

pub fn from_write(
  write: fn(a, default_controller.DefaultController) -> b,
) -> WritableStream(a)

Creates a WritableStream from only a write callback — use when the sink just needs to handle incoming chunks. If the callback returns a Promise, the stream waits for it before accepting the next chunk.

get_writer

</>

pub fn get_writer(
  stream: WritableStream(a),
) -> Result(writer.Writer(a), stream.StreamLifecycleError)

Acquires a Writer that locks the stream. Returns Locked if the stream is already locked.

is_locked

</>

pub fn is_locked(stream: WritableStream(a)) -> Bool

Checks whether the stream is locked to a writer.

new

</>

pub fn new() -> Builder(a)

Creates a Builder with no underlying-sink callbacks set.

with_abort

</>

pub fn with_abort(
  builder: Builder(a),
  abort: fn(dynamic.Dynamic) -> b,
) -> Builder(a)

Registers the abort callback that runs if the stream is aborted. Receives the abort reason. If the callback returns a Promise, the stream waits for it before resolving the abort.

with_close

</>

pub fn with_close(
  builder: Builder(a),
  close: fn() -> b,
) -> Builder(a)

Registers the close callback that runs once after all writes complete. If the callback returns a Promise, the stream waits for it before resolving the close.

with_queuing_strategy

</>

pub fn with_queuing_strategy(
  builder: Builder(a),
  strategy: stream.QueuingStrategy,
) -> Builder(a)

Sets the queuing strategy controlling backpressure on the stream’s internal queue. Without this, the stream uses the default strategy (chunk count, high water mark of 1).

with_start

</>

pub fn with_start(
  builder: Builder(a),
  start: fn(default_controller.DefaultController) -> b,
) -> Builder(a)

Registers the start callback that runs once at construction. Use to acquire resources or set up state. If the callback returns a Promise, the stream waits for it to resolve before accepting writes.

with_write

</>

pub fn with_write(
  builder: Builder(a),
  write: fn(a, default_controller.DefaultController) -> b,
) -> Builder(a)

Registers the write callback that runs for each chunk written to the sink. If the callback returns a Promise, the stream waits for it before accepting the next chunk.